Prolon fast mimicking diet


A strange diet is designed to slow aging by mimicking fasting — here’s how it works and what people eat

  • There are powerful health benefits associated with fasting, including disease-fighting changes in the body, weight loss, and potential anti-aging effects.
  • To get the health benefits of fasting without cutting food out entirely, one anti-aging researcher has designed a diet where people dramatically reduce their caloric intake for five days at a time and only eat specific meals for those days.
  • The idea behind this “fasting-mimicking diet” is for people to see the same changes in their bodies that they would if they fasted for those five days.
  • Meal kits designed to give people the right ratio of nutrients for their fasting-mimicking days are expensive, costing between $250 and $300.

When people stop eating for a time, it triggers physical changes in the body.

Going without food for too long is, of course, dangerous — or fatal. But the potential health benefits of fasting go beyond weight loss. The practice may stave off some of the effects of aging, prolonging life and preventing diseases including some forms of cancer.

Those observed health effects have led many people to try eating regimens like intermittent fasting — in which people go without food for 12 to 18 hours in a day or for 36 hours each week.

But as beneficial as fasting might be, it’s hard to do. Even intermittent fasting schedules are inconvenient and hard to adhere to over time. Plus, medical professionals generally don’t recommend that people go days without eating.

To help people achieve the benefits of fasting while still letting them eat normally most days, Valter Longo, the director of the Longevity Institute at the University of Southern California, has designed a diet called the “fasting-mimicking diet.” This plan lets people eat what they want most of the time, but every so often, they’re supposed to cut calories drastically and eat a specific blend of nutrients for five days.

Through a company called L-Nutra, Longo sells what he calls the ProLon meal kit, which he says his research indicates has the right mix of nutrients to mimic the effects of fasting. Eat set of meals costs between $250 and $300, depending on how many kits are purchased at a time.

According to a report in Bloomberg, more than 52,000 people have tried ProLon so far. But whether purchasing a meal kit is necessarily better than other fasts — or whether it really has the long-term health effects Longo and others hope — is not yet proven.

What’s in the box

The ProLon meals are plant-based and low-protein — the kit includes soups, bars, crackers, olives, drinks, and supplements. The meals are designed to theoretically trick your body into going into “fasting mode” while still getting some food.

Nutritional information for meals for a 180-200 pound patient from the ProLon patent. ProLon patent.

The exact foods can vary depending on the weight of the subject, but the basic idea is that people consume approximately 1,100 calories the first day and 750 calories on days two through five.

In one study of the diet, participants consumed 1,090 calories on day one (10% protein, 56% fat, 34% carbohydrate). For days two through five they consumed just 725 calories (9% protein, 44% fat, 47% carbohydrate). Most of those carbohydrates came in the form of vegetables.

In a story for Stat, Usha Lee McFarling detailed exactly what she ate during the five days of the diet.

Beverages included spearmint and hibiscus tea and a kind of energy drink.

Worth it?

The fasting-mimicking diet is supposed to be about more than weight loss. The goal is that by affecting various biological pathways, especially one called insulin-like growth factor-1, or IGF-1, people can better regulate blood sugar and gain some protection from cancer and other diseases.

But more research is needed before scientists can definitively say that this diet — or any fasting diet — reduces risk factors for these diseases over the long term.

The data that exists so far is promising, though. Human trials of the fasting-mimicking diet have shown that at least in the short term, risk factors for disease seem to go down, people lose weight and fat, and the diet appears to be safe.

Longo previously told Business Insider that he thinks this sort of fasting regimen should become part of medical care, the sort of thing your insurance might cover. (For now, people are supposed to get approval from a dietitian or medical professional before purchasing ProLon.)

But at the current price point, the ProLon meal kits are not affordable for many people. More research will be needed to tell if this sort of fast can truly transform health.

LOS ANGELES — The box is lovely, sleek and white. But it’s so small.

I’ve decided to try the ProLon diet — five days of “mimicking fasting” that is supposed to help me lose weight, trim belly fat, drop my cholesterol and glucose levels into healthier zones, and even slow aging. I’ve been researching the science behind fasting — check out my full story on that topic here — so I’m excited to try it myself.

But the box is so small. Not much larger than a shoebox, it contains all the food and drink, other than water, that I’ll get for five days. I sift through the futuristic-looking — and tiny — packets of olives and freeze-dried soups, kale chips, and nut bars. I love food so much. I’m a little bit worried.


The diet consists of an ultra-low-calorie blend of proteins, carbohydrates, fats, and nutrients that’s meant to trick the body into thinking it is fasting, but with less discomfort or risk than a true water-only fast. That’s according to its inventor, biochemist Valter Longo, the director of the Longevity Institute at the University of Southern California.

He’s launched a company, L-Nutra, to market the diet; it’s sold for $300 per box or $750 for three boxes, if you’re inclined to repeat the five-day fast every few months. (L-Nutra provided one box to STAT at no cost.)

Fasting, Longo says, pushes the body to burn fat, rejuvenates cells, and lowers risk factors for a host of diseases. I’ve read the scientific studies and there’s ample evidence that fasting can have great benefit for research animals, such as the mice in Longo’s lab.

The evidence for human benefits, though, is more speculative. Short-term studies have shown that fasting can improve certain data points in human subjects (such as lowering cholesterol levels), but there’s no proof yet that such improvements are sustained in the long run — or that they’ll lead to clinical benefits such as fewer heart attacks or longer lives.

There’s also no proof that Longo’s particular blend of foods works any better than any other low-calorie diet or intermittent fasting regime.

So I’m going into this armed with skepticism … but also, a great deal of curiosity. A 40-something mother of two, I’m not technically overweight but a good 15 or 20 pounds over my ideal weight. I want to know what effect the diet will have on my health.

Also, whether I’ll have the willpower to stick with it.


Most people can choose any five-day period for the diet, so they can avoid big social events or strenuous athletic activities. But I need to diet on five specific days because I’m taking blood tests immediately before and after to gauge how the diet affects my body. (I get the tests done at USC, so Longo can pull the results, but STAT pays for the lab work.) Because of poor planning on my part, the first day of my fast falls on Mother’s Day.

I love food so much. And the box containing my diet for the next week is so small. I’m a little bit worried.

So the one day of the year I normally get breakfast in bed, I get nothing. Which makes me grumpy. I make myself a cup of spearmint tea. My breakfast will be an “L-Bar” — a 280-calorie nut-based bar. Since we’re going on a hike, I decide to wait to eat the bar in case I get hungry while we’re out. It’s not a great start.

I open the bar mid-morning, while hiking. It is delicious. A blend of macadamia nut butter, almond meal, and coconut, it tastes like a dessert. I eat half, slowly, and save the rest for later.

I am getting grumpier. I am also starting to get a bad headache. I think it’s because I haven’t had any caffeine, but USC research nutritionist Mahshid Shelehchi, who is supervising my fast, tells me that it’s normal to get a headache while fasting. Even non-coffee drinkers get them.

Welcome to my lunch: freeze-dried soup, a vitamin, and a handful of olives. Usha Lee McFarling/STAT

Lunch is tomato soup that I microwave, olives, and kale-and-seed crackers with a kick of pepper. It all tastes pretty great. My afternoon snack is another nut bar — I could get used to these, I think — and spearmint lemon tea. Dinner is another freeze-dried soup, minestrone. I deeply resent the 120-calorie soup as I cook it. This is not the Mother’s Day dinner of my dreams. At least I get dessert — a “Choco Crisp Bar” that’s delicious. All four bites of it.

With my headache roaring, I decide to turn in earlier than usual.

I am getting grumpier. I am also starting to get a bad headache.

The first day’s diet contained 1,150 calories. It was hard, but not impossible. Tomorrow I have to drop to 800 calories. I’m not sure I’ll make it.


The 800-calorie days all include a bonus: A glycerol solution you mix with water that serves as an energy drink to help you get through the day. I flavor mine, as advised, with a sachet of hibiscus tea from the box. It’s crazy bright pink but because it staves off hunger, I can tell it is going to become my best friend.

I drink my spearmint tea, trying hard not to look at my cappuccino machine, which seems to beckon me from across my kitchen. Being Californian, I also really want my avocado toast. Instead, I unwrap a nut bar.

Then it’s off to USC, where I have a busy day visiting Longo’s lab. I end up staying a long time so I don’t even get to eat my lunch of mushroom soup and olives until about 3. I feel OK, considering. When I realize I get olives with my afternoon tea also, I’m thrilled. It seems like a bounty.

My entire family is obsessed with my fasting diet — and not all that helpful.

My son asks: “Will you poo?” (Constipation is a side effect; I survived.)

My husband decides to make his childhood favorite meal for dinner — sloppy Joes. While I eat my “Quinoa Mix Soup,” my family raves about how good their sloppy Joes are. “These are so good, they could be served in the finest restaurants of Barcelona,” my husband says. I am sad.

I do get a Choco Crisp Bar for dessert. And I don’t even miss having wine with dinner. I crawl into bed early, with laptop, and start devouring episodes of “Queen of the South.” Thank you, Netflix, for giving me something to binge on.

The author (left) and a friend enjoy burgers and pulled pork sandwiches (with fries!) after skiing. None of that would pass muster on the fasting diet. Peter Dickinson


Tuesday is my hungriest day. There is no afternoon snack, no Choco Crisp Bar. Just one nut bar, tomato soup, kale crackers, minestrone soup, and the energy drink, which I carry everywhere like a security blanket.

I need to finish up an article and I feel a little dopey, so I admit to the scientist I’m interviewing that I’m on a fasting diet. She’s intrigued and wants to know all about the biochemistry behind it. Everyone, actually, wants to know about this crazy diet I’m on.


Wednesday, I have a busy day shadowing several groups of elementary school kids for another story I’m writing. It’s a lot of walking, for hours, and I have to occasionally sit and rest in the shade. I wonder if this is what it feels like to be old. Shelehchi advised me that I might not want to drive while fasting, for safety, but between work and my kids’ many activities, that’s just impossible. I do skip my exercise classes.

It’s a lot of walking, and I occasionally have to stop and rest. I wonder if this is what it feels like to be old.

On Wednesday night, my husband has a work dinner that happens to be at my favorite restaurant. (I’m mad and jealous.) So I have to shop and cook for the kids. I’m worried about going into a grocery store while fasting, so I steel myself out in the Trader Joe’s parking lot. I take several gulps of energy drink and walk in the store.

It’s actually not that hard. I look at the food — the shrink-wrapped meats, the frozen pizzas laden with cheese — and it all looks kind of … disgusting. I don’t want to eat any of it.

I could maybe use an extra nut bar, but I’m OK with my soup. And my Choco Crisp Bar.

I could get used to these nut bars. They taste like dessert. Usha Lee McFarling/STAT

Cooking dinner for my kids is a breeze. I don’t feel hungry anymore. I kind of love having all my meals planned out for me and so easy to prepare. I even feel a little spoiled. Best of all, my headache has disappeared. I thought I would miss normal food and wine with dinner. (No alcohol is allowed on the diet.) But what I miss most, still, is coffee.


Thursday is easy. I have a lot of energy, which Shelehchi says tends to happen after the initial fasting days. She even does her kickboxing classes while she’s on the fast. (Initially unconvinced by the diet, she came around after seeing data from the studies she helps Longo run and now uses the diet several times a year.)

I run some errands and end up staring at a man eating Mexican food out of a styrofoam container. I want to grab his food. Maybe it’s time to return to the world of the eating.

I can’t eat Friday until after my follow-up blood test in the morning, but it’s not food I care most about. I’m plotting how to get my cappuccino as soon as possible after my blood is drawn.

You’d think I would want to binge on food after doing the diet, but the coffee is enough. Which is good, because Longo advises transitioning your stomach back to normal food with soups, juices, and light meals on the first day after the diet.


After the blood draw, I sit and chat with Shelehchi at a coffee shop near the clinic. I’ve lost nearly 4 pounds. I feel great. Shelehchi is not surprised. She says my body is now in ketosis, or fat-burning mode, and I should still keep seeing benefits for several days during “refeeding.”

I kind of love having all my meals planned out for me and so easy to prepare. I even feel a little spoiled.

I tell her one benefit of the diet is that I realize I can eat a lot less food than I do — that right now, much smaller portion sizes and light soups for lunch seem a really easy way to keep losing weight. It’s a common side effect of the diet, she says, adding: “It makes you think about every single thing you put in your mouth.” She said many women (like me) who carry extra fat they never lost after pregnancy are able to lose it using this diet.

I knew my cholesterol was on the high side going into the diet — I’d recently had a physical and had elevated cholesterol for the first time in my life. My doctor said it was probably due to the high-protein diet I had been trying, and Longo agreed. “It’s the worst idea,” he said. “The absolute worst.”

So, when Longo calls later with my blood test results, I’m delighted to hear that my overall cholesterol and my LDL, or bad, cholesterol dropped during the five days of the diet, though my triglycerides didn’t. I also saw big improvement in my levels of IGF-1, or insulin-like growth factor-1, which is linked to higher rates of cancer. (Longo says mine might have been elevated originally because of that high-protein diet.) It’s not clear if lowering IGF-1 translates into better health or longevity, but it can’t hurt.

I’m a cynical journalist and I’m known to be skeptical — especially about faddish health food claims, heavy marketing, and quick fixes. But this diet seems to have worked for me in the short-term. Nearly one month after ending the diet, I’m still eating much smaller portions, many of them plant-based, and limiting my protein intake. I’ve lost three additional pounds.

And I’m still savoring every cup of coffee.

I tried Prolon’s starvation diet so you wouldn’t have to

My bitterness peaked midway through day four of the “Fast-Mimicking Diet,” when a parent arrived at my daughter’s softball game with doughnuts. As little girls and fellow coaches crowded around the box, I stood apart, glumly sipping out of my special water bottle with its “proprietary” blend of nutrients.

For breakfast, I’d consumed a nut bar the size of a small cracker and a couple of vitamins. Lunch was five olives from Seville.

Frankly, I’d begun to resent Valter Longo, the inventor of Prolon, the five-day, $250 fad diet causing my misery. True, the Italian-born biochemist had seemed perfectly nice when I’d reached him at his office at the University of Southern California’s Longevity Institute a few days before to speak with him about the science behind the diet and what it might do for my general health and longevity. He had patiently explained how the diet would temporarily shift my body into a starvation state that would prompt my cells to consume years of accumulated cellular garbage before unleashing a surge of restorative regeneration. Getting rid of garbage had sounded like just what I needed. But now I blamed him for my predicament. I wanted a doughnut.

My Prolon “meal kit” had arrived in a white cardboard container a little bigger than a shoebox. Inside I’d found a meal program card spelling out the menu, a large empty water bottle emblazoned with the word “Prolon,” and five smaller cardboard boxes, each labeled with a corresponding day. I opened the box for day one, billed as a higher-calorie “transition day,” and was pleasantly surprised. It didn’t look so bad. I’d be sampling many of the diet’s highlights: a small packet of kale crackers, powdered tomato soup blend, algae oil supplements, a bag of olives, herbal tea, and not one but two nut-based bars (albeit distressingly small).

When I opened up day two, however, I began to get a better sense of what I was in for. One of the puny nut bars had been replaced by a glycerin-based “energy” drink, which I was instructed to add water to and sip on throughout the day. There was more herbal tea—hibiscus, mint, and lemon (I don’t even like herbal tea)—plus a couple more powdered-soup packs and two tiny packets of olives. Where was the rest of it?

“We give you quite a bit of food—just over 800 calories,” a trim, youthful nutritionist explained unironically in a YouTube video I pulled up to make sure there was no mistake. The goal of Prolon, he explained, is to trick the body into thinking you are fasting, prompting it to “suppress all of the same pathways as if you were doing a full fast.”

“By day three your body has activated all of the benefits and then spends the rest of the days optimizing, regenerating, rejuvenating,” he added cheerfully. “So you can really expect to feel the benefits on day four.”

Valter Longo, Prolon inventorCourtesy photo

The lesson of Biosphere 2

The idea that starving yourself while still taking in crucial nutrients will let you live longer is not new. The practice, called caloric restriction, is the only proven way to extend life that works in a wide variety of creatures, from worms to rodents to primates. And it was already of interest to biologists when Longo was first starting out in the field, almost 30 years ago.

At the time, there were few people more identified with the radical diet than Roy Walford. A larger-than-life figure, Walford had already demonstrated in his UCLA lab that he could double the life span of mice by drastically restricting their caloric intake. He had also published a number of popular books on the topic, among them The 120 Year Diet and Beyond the 120 Year Diet, and would follow a strict 1,600-­calorie diet himself for the last 30 years of his life (the US Department of Health recommends 2,800 calories a day for an active middle-aged man). He weighed in at 130 pounds (59 kilograms) for most of that time, far below the average weight for someone 5’9″ (175 centimeters) tall.

When Longo arrived in Walford’s lab to begin his PhD work in 1992, Walford was on temporary leave. Several months earlier, he’d gone to the Arizona desert to serve as one of eight “crew members” in a three-acre (1.2-hectare) complex of hermetically sealed domes known as Biosphere 2. The two-year experiment in communal living was billed as a test of the kind of home that might one day be built and used for the colonization of space. Soon after entering the biosphere in 1991, the crew members discovered they could not grow nearly as much food as they had anticipated. It was Walford, the crew physician, who persuaded them to follow a severe calorie restriction diet—a decision that garnered worldwide media attention as they staggered out of the biosphere in 1993, gaunt and sickly.

Walford died in 2004, at 79, of amyotrophic lateral sclerosis, a.k.a. motor neuron disease or Lou Gehrig’s disease—a condition, Longo notes, that many suspected was the result of the two years of extreme calorie restriction he endured in the biosphere. It’s a theory Longo takes seriously.

“We don’t know if that was the cause,” he says. “But I was there when he came out of the biosphere, and he looked sick and so did everybody else. Maybe he paid a price for that. We don’t know what the connection is with motor neuron disease. But it’s possible his neurons couldn’t handle this extreme situation for years and years and years. Maybe it combined with something else.”

The lesson was clear: while caloric restriction might make you live longer, doing it for extended periods was a problem, and probably not practical for most people.

Biological house cleaning

In any case, at the time Longo was less interested in the association between diet and longevity than in what he considered to be a fascinating by-product of extreme calorie restriction. Longo discovered that when he starved bacteria and yeast, they not only lived far longer than their well-fed counterparts but entered a protective state that seemed to shield them from environmental stress. When exposed to hydrogen peroxide, yeast in starvation mode were between 60 and 100 times more resistant to cellular damage than yeast that had been taken from an environment rich in glucose to feed on.

That was surprising. Wouldn’t a cell weakened by starvation become less resistant to damage, rather than more? But in the years that followed, a consensus emerged that explained both Longo’s discovery and other researchers’ findings that lab animals fed a calorie-restricted diet lived longer.

In a well-fed state, our cells and those of other multicellular organisms invest energy in reproduction and regeneration. But when food is scarce, those functions shut down, and the cell diverts its energy to feeding and protecting itself; it takes far less energy to protect the cells you already have than to build new ones.

To do so, the body revs up a host of protective pathways. In the case of Longo’s yeast and bacteria (and eventually mice), he and others would later show, the organisms make enzymes that neutralize free radicals—molecules with unpaired electrons that can damage other cells. Other proteins and enzymes are produced that ensure proteins don’t misfold, and in every cell, the cellular machinery devoted to repairing its own DNA kicks into overdrive.

In more complex organisms like mice or humans, the body still needs calories to keep the heart beating, the brain thinking, and the muscles contracting. To get them, it engages in a process called autophagy (an ancient Greek word that means “self-­consumption”), breaking down the body’s own cells and recycling their components. But this autophagy is not random.

“It tends to begin by eating proteins that are misfolded or denatured,” explains Eric Verdun, the president and CEO of the Buck Institute for Research on Aging. “There is a house-cleaning aspect to it. It consumes itself, but it consumes the proteins that need to be cleaned out first.”

Forced to turn inward for energy sources, the body hunts down, eats, and recycles its own cellular garbage, in the process removing debris that can prevent cells from operating efficiently.

Starving cancer cells

A Prolon meal kit comes in a white cardboard container a little bigger than a shoebox. Inside is a meal program card spelling out the menu, a large empty water bottle, and five smaller cardboard boxes, each labeled with a corresponding day.
1. The diet tricks your body into starvation mode, but tries to make it tolerable.
2. Each day of food comes in its own distressingly small cardboard box.
3. Kale crackers were the author’s favorite.
4. Prolon is big on olives from Seville, which taste great but are not very filling.
5. You are allowed to add lemon to enhance the flavor if necessary.
Bruce Peterson

Longo was fascinated by this process, and he would spend the next two decades helping to identify the genes and biological pathways at work. As he did so, he began to recognize something unexpected. Many of the genes involved were also prominent in the cancer literature.

In the cancer field, they were known as “proto-oncogenes”—the very same genes that, when mutated, had the power to transform a normal cell into a cancerous one, by essentially wedging the cell’s regeneration machinery permanently into the “on” position and causing it to divide and proliferate uncontrollably.

That gave Longo an idea. He had already shown that starvation could cause all an organism’s normal cells to enter a protective state. But cancer cells aren’t normal cells. One of the hallmarks of cancer is that the cells do not respond to biochemical signals suppressing their growth. What would happen, Longo wondered, if he put mice into starvation mode before exposing them to chemotherapy? If the normal cells went into a protective state but the cancerous ones did not, drugs could kill the cancer with less risk of damaging normal tissue.

Longo administered high doses of the chemotherapy drug doxorubicin to yeast. He found that under starvation conditions, normal yeast cells became a thousand times more resistant to stress, while cancer cells were exposed to the full brunt of the poisons. When Longo repeated the test on mice, starving one group for 60 hours prior to the chemo, the results were dramatic. Every single one of the normal mice died. Every single one of the starved mice lived.

But when Longo began reaching out to clinicians who worked with cancer patients, he encountered unexpected resistance. “We thought, ‘Of course. Everybody is going to do it. It’s going to be easy,’” Longo recalls. “It took us five years to recruit 18 patients. It was water-only fasting. Completely free. Don’t eat. Just drink. Nobody wanted to do it. Everybody thought it was a disaster.”

Facing defeat, Longo and his team groped for alternatives and quickly hit on a better idea: perhaps they could design a diet that aimed to trick the body into thinking it was fasting, without actually starving. Longo knew that if he made a low-carbohydrate diet lacking glucose and certain key amino acids—in other words, most proteins and all carbs were out—the body would still enter its protective state.

Longo created a company, L-Nutra. By 2014, his lab had produced its first prototype. And in 2015, he published a study demonstrating that middle-aged mice on the fast-mimicking diet had far fewer tumors and were protected against cognitive decline. By then researchers in Leiden in the Netherlands had finally signed up enough volunteers to show that water-only fasting helped protect human patients from the ravages of chemotherapy. They agreed to begin testing a version of Longo’s diet on 125 cancer patients undergoing a similar chemo regime.

Longo says more than 40 trials are currently under way, at a wide variety of institutions. Not all of them are for cancer; there are also studies for Crohn’s disease, Alzheimer’s, and Parkinson’s.

The danger of success

Longo never forgot his roots in Walford’s lab. He knew that calorie restriction had “incredible effects,” but he also knew a strict diet had problems. Immunity was lowered, because the body could not produce white blood cells as quickly. Besides, “very few people can stick to calorie restriction,” he says. “Maybe one in ten thousand in the United States. It was not feasible for the great majority of the people.”

Longo was convinced, however, that periodic calorie restriction had some of the same health benefits as being on the diet full time—benefits worth the effort, if one could endure hunger pangs for a few days.

He decided he had to commercialize the diet—not just for the benefit of cancer patients, but because he also wanted it taken seriously as a tool for promoting healthy aging. “To me, it was very clear that it had to be somehow made into a drug-like product,” he says. “I realized early on that if there wasn’t a product, it would be very difficult for doctors and every health-care professional to take it seriously, and also to implement it. Doctors are used to something that has been tested clinically. They can’t say, ‘Here is a diet somebody at USC used.’”

So in September 2016, Prolon, the diet I tried, was born. Research on the “fast-mimicking diet” is still limited. So far, the most prominent publication on it is a 2017 study in the journal Science Translational Medicine, in which 71 healthy adults in the United States were given the Prolon diet for five consecutive days once a month for three months. The results established that the diet not only was safe but reduced things like body fat, blood pressure, insulin-like growth factor, low-density-lipoprotein cholesterol, and triglycerides, all of which are associated with aging and age-related diseases. It’s also far easier to stick to than a straight water starvation fast.

The sparseness of research data in humans has done little to dampen enthusiasm. Today Prolon is successful beyond anything an academic could reasonably hope for. The product—which, according to a company website, promises to “ into a protective and stress resistant mode; remove damaged cells and tissues; and promote self-repair through cellular regeneration and rejuvenation”—is all the rage in Silicon Valley. It’s sold in 15 countries and has been tried by more than 150,000 people.

Instead of doing backflips, however, Longo has grown increasingly concerned in recent years about what this commercial success might do to his scientific reputation. In 2017, after a series of articles about the product—one of which described Longo as “sounding like a snake-oil salesman” although it was fairly positive about the research—he announced he would no longer accept consulting fees and would donate his shares in the company to charity.

“All the decisions are made by the CEO,” he says. “I act as a professor … I am a scientist, and my heart is in the science and making sure it works. And the company’s heart is in a different place. Once you start having investors and you start having shareholders, it’s different.” He adds, “If I’m doing anything, I’m trying to get the company to do the right things, and sometimes I’m telling them, ‘Look, can you lower the price?’ I’m fighting for the people I see coming to the university to do the trials. I’m the watchdog of the company.”

Longo is not the only anti-aging scientist who has found himself the subject of unflattering media coverage, or attacks from rivals criticizing products he’s involved with as untested. The others deal with it in different ways. Nir Barzilai, who directs the Institute for Aging Research at the Albert Einstein College of Medicine, founded a publicly traded company called CohBar that focused on peptides involved in aging and age-related diseases. He stopped doing any research in the area to eliminate the appearance of conflict when he talks about it in the media. He has a financial stake, in other words, but his scientific career is now focused on other questions.

“You get into lots of conflict,” Barzilai says. “I’m in interviews. I’m on television. I didn’t want anybody to say, ‘You’re promoting your research and your company.’”

Others take a more relaxed attitude. Leonard Guarente, an MIT professor and prominent anti-aging researcher, cofounded a company called Elysium to sell supplements designed to work on a family of proteins called sirtuins that have a role in aging, as he discovered in the early 2000s. His stated goal is to use the profits to follow up with scientific studies that document the effects on humans. He’s not afraid to own it, despite the media backlash. “I don’t know if it bothers me as much as it bothers some others,” he says.

In a field badly tarnished by hype and false claims, the scientists face a real dilemma. Their products, unlike many others on the market, have legitimate science behind them. It’s early days, but their anti-aging approaches could work. “Our goal in this research is to stop the age-related diseases,” says Barzilai. “If we’re not going to do that, who’s going to do it, exactly? It cannot happen without us.”

Minus 8 pounds and happy

After five long days on Prolon, I awoke one morning to a day that promised as much soup, juice, and light meals of legumes and pasta as I could handle. Day six is a “transition” day, and dieters are encouraged not to binge. I can’t say I followed the suggested instructions. My first stop was Whole Foods, where I consumed an entire packet of Frisbee-size puffed-rice discs.

I felt great. My wife told me I seemed to be unusually energetic. I had lost eight pounds (nearly four kilograms) over five days, too. Overall, it hadn’t been too bad. I’d been reading about and reporting on different biological pathways involved in healthy aging on and off for several years, and the scientific claims made about Prolon were consistent with much of what I had read.

It wasn’t easy. I’d been hungry, grouchy, and bitter. But I never could have completed a real water-only fast for five days. And in the days that followed, it seemed to me I really did feel far better than I had before. Even if I was imagining the effects, which I don’t think I was, I stayed away from sugars and junk food for weeks afterward. That alone is reason enough to do it again—which I plan to after the suggested three-month interval has passed.

By then, the softball season will be long over.

Adam Piore is a freelance journalist based in New York. He is the author of The Body Builders: Inside the Science of the Engineered Human, about how bioengineering is changing modern medicine.

ProLon Fasting Mimicking Diet Review: Does It Work for Weight Loss?

Unlike the majority of diets on the market, the ProLon Fasting Mimicking Diet is supported by research.

Plus, multiple research studies have demonstrated the health benefits of similar fasting methods.

May Promote Weight Loss

A small study led by Dr. Longo compared people who completed three cycles of the ProLon Fasting Mimicking Diet over three months to a control group.

Participants in the fasting group lost an average of 6 pounds (2.7 kg) and experienced greater reductions in belly fat than the control group (4).

Though this study was small and led by the developer of the ProLon Fasting Mimicking Diet, other studies have shown that fasting methods are effective in promoting weight loss.

For example, one 16-week study in obese men found that those who practiced intermittent fasting lost 47% more weight than those who continuously restricted calories (5).

What’s more, very-low-calorie diets have been proven to encourage weight loss (6, 7).

Still, evidence that the ProLon Fasting Mimicking Diet is more effective than other low-calorie diets or fasting methods is currently lacking.

May Reduce Blood Sugar and Cholesterol Levels

The same small study led by Dr. Longo that linked fast mimicking to fat loss also observed that the Fasting Mimicking Diet group experienced a significant drop in blood sugar and cholesterol levels.

Cholesterol was reduced by 20 mg/dl in those with high cholesterol levels, while blood sugar levels dropped into the normal range in participants who had high blood sugar at the beginning of the study (4).

These results were also demonstrated in animal studies.

Four days of the diet every week for 60 days prompted regeneration of damaged pancreatic cells, promoted healthy insulin production, reduced insulin resistance, and led to more stable levels of blood glucose in mice with diabetes (8).

Although these results are promising, more human studies are needed to determine the diet’s impact on blood sugar.

May Reduce Inflammation

In a study in people practicing alternate-day fasting for the religious holiday of Ramadan, proinflammatory cytokines were significantly lower during the alternate-day fasting period, compared to the weeks before or after (12).

One animal study found that the Fasting Mimicking Diet may be effective at reducing certain inflammatory markers.

Mice with multiple sclerosis were placed on either the Fasting Mimicking Diet or a ketogenic diet for 30 days.

The mice in the fasting group had significantly lower levels of ifnγ and the T helper cells Th1 and Th17 — proinflammatory cells associated with autoimmune disease (13).

May Slow Aging and Mental Decline

One of the main reasons Dr. Longo developed the Fasting Mimicking Diet was to slow the aging process and risk of certain diseases by promoting the body’s ability to self-repair through cellular regeneration.

Autophagy is a process in which old, damaged cells are recycled to produce new, healthier ones.

Intermittent fasting has been shown to optimize autophagy, which may protect against mental decline and slow cellular aging.

A study in mice found that short-term food restriction led to a dramatic increase of autophagy in nerve cells (14).

Another study in rats with dementia showed that alternate-day food deprivation for 12 weeks led to greater reductions in oxidative damage to brain tissue and reduced mental deficits compared to a control diet (15).

Other animal studies have demonstrated that fasting increases the generation of nerve cells and enhances brain function (16).

What’s more, intermittent fasting has been shown to decrease insulin-like growth factor (IGF-1) — a hormone that, at high levels, can increase the risk of certain cancer, such as breast cancer (17, 18).

However, more human studies need to be carried out to fully understand how fasting may impact aging and disease risk.

Summary The Fasting Mimicking Diet may promote weight loss, enhance autophagy, and reduce blood sugar, cholesterol, and inflammation.

Mimicking the Fasting Mimicking Diet – My 5-Day Experiment

There are numerous studies that demonstrate the benefits of periodic, short-duration fasting, such as weight loss, improved insulin sensitivity and brain function, immune system regeneration, and longevity. I’ve been a fan (and practitioner) of intermittent fasting for several years, but other than an occasional 24-hour liver cleanse or protein fast, I had never done any extended fasting.

My original plan was to do a “traditional” water fast, where nothing but water is consumed for a period of 3-5 days. However, during my research I began looking for ways to get all of the benefits of a water-only fast, but in a way that was “easier” (both mentally and physically), safer, and would minimize catabolic effects (loss of muscle mass). Enter the “fasting mimicking diet”…

What is the Fasting Mimicking Diet?

The Fasting Mimicking Diet (FMD) received a lot of media attention when it was introduced a few years ago. In a study that was published in Cell Metabolism (and funded by the National Institute of Aging), researchers found that cutting daily calories in half for just four days every two weeks reduced biomarkers for aging, diabetes, heart disease and cancer with no adverse effects. FMD was tested on yeast, mice, and humans and the results remained consistent among all three groups.

The FMD describes itself as:

…a plant-based diet program designed to attain fasting-like effects while providing micronutrient nourishment (vitamins, minerals, etc.) and minimize the burden of fasting. It comprises proprietary vegetable-based soups, energy bars, energy drinks, chip snacks, chamomile flower tea, and a vegetable supplement formula tablet.

The primary researcher, Dr. Valter Longo, owns a patent on the FMD, and has since began selling a dietary product under the name ProLon.

Bonus: Free DIY FMD Spreadsheet

Get a FREE copy of my FMD spreadsheet that you can use and customize!

“Mimicking” the Fasting Mimicking Diet

The patent filing provided enough information to allow me to inexpensively hack together my own “close enough” version of the FMD. The nutrition rules of the FMD can be summarized as follows:

Fasting Mimicking Diet Cycle:

The fast is then followed by a 25-day “refeeding” period (return to regular diet). The study recommends repeating the 5-day fasting/25-day refeeding cycle 3-4 times in a row to maximize effects.

Fasting Mimicking Diet Nutrient Guidelines:
  • Low protein and low carbohydrate, with no or minimal animal-derived products
  • High micronutrient content (30-50% of recommended daily intake of vitamins, minerals, and essential fatty acids, with 50% of them coming from natural sources)
  • Proteins from plant-based sources
  • Carbohydrates ideally from complex carbohydrate plant sources
  • Fats primarily from “healthy” oils (coconut oil, olive oil) and nuts (almonds, walnuts)
  • Less than 30g of sugars on day 1, and less than 20g of sugars on days 2-5

My Fasting Mimicking Diet Meal Plan

I put together the following eating plans that got me pretty close to the target macronutrient requirements, which I would split into AM and PM “meals.” My goal was to limit ingredients and keep things as simple as possible. Again, feel free to check out my Google Spreadsheet for detailed nutrient profiles. I also came across this useful list of Fasting Mimicking Diet recipes.

My primary nutrition sources were avocados (Mexican Hass variety) and green superfood powder (to provide additional micronutrient content), along with some white rice raw cauliflower and sweet potatoes (in a bit I will explain why I took out white rice). I also had a teaspoon of sea salt each day (mixed in a glass of water) to assist with electrolytes and adrenal support during the fast.

I drank around 1.5-2 liters of spring/high alkaline water each day along with a cup or two of chamomile flower tea (which subjects in the original study were allowed to drink liberally). And each morning I allowed myself 2 cups of black coffee with some cinnamon sprinkled in (in retrospect, I would have cut my coffee consumption because according to ProLon’s FAQ, “Because coffee can interfere with the beneficial effects of the diet, it is not recommended to be consumed… however, if one must have coffee, we recommend minimizing coffee consumption to 1 cup per day.”)

Measuring out a day’s worth of FMD meals

My Fasting Mimicking Diet Results

To establish pre-FMD baselines, one week prior to starting the FMD I cycled off of all supplements. My friends at InsideTracker were kind enough to offer me complementary pre/post blood testing (I’ve included a link and discount code at the end of this post). Also, during my fast I refrained from any physical activity – no workouts or sports.

I tracked a number of markers a) prior to starting; b) during; and c) one week post FMD, and saved my experiment data in a Google Spreadsheet, which you are welcome to explore. Feel free to make a copy of it if you decide to replicate my experiment!

Glucose and Ketones

I was very pleased with the effect FMD had on my fasting glucose and blood ketones. While there were rises and dips in my PM glucose and ketone values (taken 2 hours after my evening meals), my morning fasting glucose levels steadily declined from ~80 mg/dL pre-FMD to the mid 40’s, while ketones steadily rose – after 1 day I was in “nutritional ketosis” (0.5 – 1.5 mmol/L), and after 3 days I got into what is called “optimal ketosis” (1.5 – 3 mmol/L). You can see a clear inverse relationship between glucose and ketone values.

On day 2, I consumed some white rice with my PM meal (mainly for the carbs), but as you can see on the chart, it resulted in a huge spike to my blood glucose (it’s the 111 value at around 45 hours). For the remainder of the fast, I substituted some raw cauliflower and sweet potatoes to bring down my glycemic load.

My fast happened to end on Easter Sunday (had my first meal around 11am, after taking my final measures), and once I began refeeding (think big Italian family meal!) I immediately fell back out of optimal/nutritional ketosis and glucose values returned to their pre-fast range.

So, while it was great to see the FMD’s effects on glucose/ketones, it was clear that my body wasn’t as keto-adapted as I had thought prior to starting the fast (even though I get into light nutritional ketosis for a short period each day). Apparently it can take anywhere from two weeks to 30 days for the body to fully keto-adapt.

Pro Tip

When “refeeding” after a 5-day FMD, start easy! Begin with a small bowl of broth and some nuts such as cashews, followed by a light, easy to digest meal a few hours later (perhaps some eggs) and return to a regular sized meal a few hours after that. Your digestive system will thank you.

The chart above shows changes to body weight, measured first thing each morning (after urinating) using my Omron scale. I was surprised to see that I only lost around 3 lbs of body weight during the FMD (171.8 lbs to 168.8 lbs), which happened very steadily and actually stabilized after day 4, but then began to rise again approximately 3 days after completing the fast.

Typically, during a traditional water fast a person will not only lose “water weight” and body fat, but there will also be catabolic effect (loss of muscle mass). One of my theories was that a FMD-type of approach to fasting would minimize the loss of muscle. Here are my results:

So, during the FMD I lost approximately 4.2 lbs of body fat, while GAINING nearly a pound of muscle! There was also a nice muscle building “rebound” effect once my fast ended and I began to exercise again. I realize that most home scales that use body impedance to measure body fat can be very unreliable, but unfortunately, for this experiment my Omron scale had to do since I didn’t have access to more accurate body composition tools such as a DEXA scan, BodPod, Inbody, etc.

Energy, Mental Clarity, and Dreaming

Overall, I maintained very good energy during the FMD. I knew from previous experience with intermittent fasting that ketosis can really provide focus and mental clarity, and by day 3 I was having some very productive days of writing, coding, and reading.

Many people claim to experience “carb-mares” (low carb-induced nightmares, or even dreaming about carbs) when switching to a ketogenic diet. In my case, I had the most frequent, vivid, and memorable dreams (not nightmares) I have experienced in a long time! Although the content of my dreams didn’t seem too profound, I could recall every little detail. Once my FMD ended, this level of dreaming and recall largely subsided.

Heart Rate Variability (HRV)

Upon waking each day I would take an HRV reading, shown in the chart below. What’s interesting to see is that there was a slight uptick in HF (sign of parasympathetic activity) each day until I broke my fast.

Another HRV measure, RMSSD, is commonly used as an index of vagally (vagus nerve) mediated cardiac control which captures respiratory sinus arrhythmia (RSA), the frequent changes in heart rate occurring in response to respiration. During inhalation, heart rate speeds up. During exhalation, heart rate slows down. RMSSD is an accepted measure of parasympathetic activity and as you can see, it correlates very well with HF of frequency domain analysis.

Blood Pressure and Body Temperature

I took my body temperature each morning upon waking, and surprisingly there was very little change during my FMD. Blood pressure trended down slightly but nothing drastic. However, I did experience what appeared to be some circulatory issues in my hands – they got rather cold by day 4 of my FMD, yet my body temperature and blood pressure were largely unchanged.

Could this be related to my blood glucose dropping so low? Or perhaps it’s the body’s attempt to maintain core body temperature so it will reduce circulation to extremities?

Blood Oxygen Saturation (SPO2)

I also tracked oxygen saturation (SPO2) each morning using an inexpensive blood oxygen sensor. I thought there would be a decrease in my SPO2 readings as the fast progressed, but my readings were consistently in the 98-99% range (sometimes even 100%).


I had my post-FMD blood test from InsideTracker done 5 days after breaking my fast.

Inflammatory Markers – C Reative Protein hs-CRP

Pre-FMD: 1.5 mg/L / Post-FMD: 0.5 mg/L

InsideTracker provided me with hs-CRP results (a marker of inflammation). hs-CRP is the “high sensitivity” version of CRP measurement, and is a better indicator of inflammation in the body than the regular CRP test. Optimal hs-CRP levels appear to be an effective predictor of healthy heart, circulatory system, blood pressure, and blood glucose.

My hs-CRP was slightly elevated prior to my FMD, but I’m convinced this was due to the lingering effects of a quadriceps injury suffered playing soccer the previous week (since acute muscle injuries/trauma/inflammation can throw off CRP numbers) and my creatine kinase value was also elevated prior to the FMD. The good news is that my post-FMD results showed my hs-CRP went down to 0.5. My creatine kinase returned to my “optimized zone” as well.

Immune System and Regeneration Markers – White Blood Cell Count (WBC)

Pre-FMD: 2.7 x10E3 µL / Post-FMD: 1.8 x10E3 µL

The original study showed the FMD to provide regenerative effects to immune systems, with more noticeable effects after several FMD cycles. I was especially interested to see if it would impact my WBC count, as my levels have been tremendously low over the past few years due to a suppressed immune system. Sadly, FMD didn’t have an effect on my WBC count – it actually went down.

Unfortunately, the testing didn’t include IGF-1 (insulin-like growth factor 1), which was one of the key markers tracked in the original FMD study (there was a significant decrease in IGF-1 among subjects). I would have liked to have tracked lymphocytes as well.


Pre-FMD: 475 ng/dL / Post-FMD: 804 ng/dL

On the positive side, one of the most surprising results was an over 325 point increase in testosterone! Along with my increase in skeletal muscle mass, this shows there is definitely a “rebound”/growth factor effect after the fast is broken and refeeding begins.

Stress Markers – Cortisol and Adrenal Function

Pre-FMD: 8.9 µg/dL / Post-FMD: 11 µg/dL

My major concern with attempting a fast was the added stress it would place on my body, specifically on my adrenals. As I mentioned earlier, I made sure to consume some sea salt every day to provide adrenal support. My cortisol level remained right smack in the middle of my “optimized” zone.

Liver Function

ALT: Pre-FMD: 38 U/L / Post-FMD: 25 U/L

AST: Pre-FMD: 35 U/L / Post-FMD: 23 U/L

GGT: Pre-FMD: 12 U/L / Post-FMD: 11 U/L

Albumin: Pre-FMD: 4.5 g/dL / Post-FMD: 4.5 g/dL

I was concerned about the effects (stress) fasting would cause to my liver, but surprisingly all of my liver markers were in my “optimal zone”:

Next Steps / Future Tweaks to FMD

Based on my results and those of my friends, I plan on making a few tweaks the next time I do a FMD:

  • Macronutrients: I would like to consume more fats, even if that means a further reduction in carb intake. I also think that the FMD shouldn’t be so “one size fits all” based only on body weight – it should take into account things such as person’s body composition (body fat, skeletal muscle mass) and pre-existing blood markers
  • Micronutrients: While my macronutrient content matched the FMD, I found it difficult to match the micronutrient content across the board without incorporating any supplements. I wasn’t too concerned with a few of the micronutrients falling below guidelines (such as Vitamin D) since it was only over a period of 5 days
  • Food Choices: Generally I was happy with the eating plan I put together, but I would like to include more broths next time (both for the nutrients as well as making me feel “full”)
  • Kidney and Liver Support: Starting on day 3, I began to experience a bit of pain in my kidneys. I believe this was due to my body detoxing. I began taking some activated charcoal, and the pain went away. I would also like to include some milk thistle to provide additional liver support.
  • Tracking and Testing: The next time I attempt FMD I will simplify my level of tracking by skipping those measures that didn’t add much value (no pH, blood pressure, SPO2, body temp). I would also do bloodwork 3 times (prior to, right after completion, and 5 to 10 days after completion) to get a better picture of my body’s state at the end of the fast versus after refeeding began. I would also like to add other markers such as IGF-1 and lymphocytes. And lastly, I would do more thorough body composition analysis (BodPod or InBody).

Conclusions/What’s Next?

Overall, I was very impressed with my FMD results. It was very much a learning experience and was much easier to get through than I had anticipated. The most difficult part was finding 5 days where I could limit any physical activity (soccer matches, gym, etc.). I was most happy with the FMD’s effects on glucose and ketones, as well as cognitive effects (focus, dreaming). Next time I do a FMD I want to include some cognitive testing in order to better quantify cognitive function.

Ideally, the FMD is supposed to be done over a period of several cycles (5 days of fasting followed by 25 days of regular diet). The literature suggests that the overall benefits (lowered inflammation and increased immune system function) will increase after each cycle. I plan on repeating the FMD in 45-60 days, incorporating some of the tweaks I outlined.

Please let me know if you have done some form of fasting or plan to fast in the future – would love to hear about your experience!

Get a FREE copy of my FMD spreadsheet that you can use and customize!

Resources and Reading:

My Fasting Mimicking Diet Data (Google Spreadsheet) – feel free to explore my data or use it for your own FMD experiment!

“A Periodic Diet that Mimics Fasting Promotes Multi-System Regeneration, Enhanced Cognitive Performance, and Healthspan”, Cell Metabolism (original FMD paper)

“Fasting condition as dietary treatment of diabetes” (original FMD patent)

The 5-Day Fast Mimicking Diet – Damien over at Quantified Body also has a great writeup (and accompanying podcast) of his experience trying to replicate the FMD. He was the one who originally brought the FMD to my attention, so it’s great to be able to have someone else to compare notes with.

Tools, Products, and Services:

Blood Glucose and Ketones: I used a Precision Xtra blood glucose/ketone meter. You’ll also need glucose test strips and ketone test strips (note that ketone test strips can get expensive)

Blood Testing: I took InsideTracker’s “Ultimate” testing plan prior to and 5 days after completing my FMD (use my code BOBTRO11012 to save 10% off your own InsideTracker tests!)

Weight and Body Composition: I used this Omron Body Composition Monitor and Scale for weight and body composition measurements.

Heart Rate Variability: I used an HRV app called HRV4Training, which I paired with a Polar heart rate monitor. SweetBeatHRV is another HRV app I recommend.

Blood Pressure: For blood pressure readings I used this Omron blood pressure monitor

Blood Oxygen Sensor: I used an inexpensive pulse oximeter similar to this one.

Body Temperature: Kinsa smart thermometer

Breath Ketones: During my fasting mimicking diet experiment I used a device called Ketonix to check breath ketones (it works by measuring acetate in one’s breath). Unfortunately, using the device correctly takes a lot of practice (consistent breaths) and I wasn’t able to see a correlation between the breath ketone readings and my blood ketones.

Urinary pH: I used these inexpensive HealthyWiser urinary pH test strips

Activated Charcoal: I took 1-2 activated charcoal capsules to help clear any toxins from my body during my FMD. Be careful because too much activated charcoal can cause constipation!

Green Superfood Powder: I used Amazing Grass Green SuperFood powder to help with plant-based micronutrient needs

Nutritional Data: I primarily used USDA nutrient data from here and here

LOS ANGELES — He knows he sounds like a snake-oil salesman.

It’s not every day, after all, that a tenured professor at a prestigious university starts peddling a mail-order diet to melt away belly fat, rejuvenate worn-out cells, prevent diseases ranging from diabetes to cancer — and, for good measure, turn back the clock on aging.

But biochemist Valter Longo is convinced that science is on his side.

Longo has spent decades studying aging in yeast cells and lab mice. He now believes he’s developed a diet that may boost longevity — by mimicking the effect of periodic fasting. So he’s packed precise quantities of kale chips, quinoa soup, hibiscus tea, and other custom concoctions into boxes that go for $300 a pop.

Longo’s ProLon diet (it stands for “pro-longevity,” he says, and not “Professor Longo”) reflects a growing interest in episodic fasting, which has been touted by celebrities such as Jimmy Kimmel and Benedict Cumberbatch and in best-selling books like “The Alternate-Day Diet.” His approach stands out because he insists he can use certain combinations of nutrients to trick the body into thinking it’s fasting without actually being on a punishing, water-only diet.

Intrigued, STAT reviewed dozens of scientific studies and talked to a half-dozen aging and nutrition experts about fasting in general and ProLon in particular. We visited Longo’s lab at the University of Southern California’s Longevity Institute, where slender black and white rodents pass their days in clear plastic boxes labeled “DO NOT FEED.” We even tried Longo’s diet for one long and rather hungry week.

Our conclusion? Fasting does appear to boost health — certainly in mice, and preliminary evidence suggests it might do so in humans as well, at least in the short term. It’s not yet clear whether that’s because abstaining from food prompts cellular changes that promote longevity, as some scientists believe — or because it simply puts a brake on the abundant and ceaseless stream of calories we consume to the detriment of our health. Either way, it can be a powerful force.

“We’re not meant to eat three meals a day — and snacks,” said Mark Mattson, a pioneer in studying the effects of intermittent fasting on the brain who runs the neuroscience lab at the National Institute on Aging.

Mice and rats on fasting regimes are slimmer, live longer, and stay smarter and physically stronger as they age. They resist tumors, inflammatory diseases, and the neurodegeneration that characterizes diseases like Parkinson’s and Alzheimer’s. They handily fight off infection and can even sprout new neurons. They don’t end up with diabetes, autoimmune disease, high cholesterol or fatty livers.

Longo, who runs labs at both USC and at at the IFOM cancer institute in Milan, believes he knows why. Fasting, he and others argue, gives cells a break to rest, renew, rebuild themselves and, essentially, take out the trash as the body shifts from storing fat to burning it. They can’t do that when the body is constantly ingesting food, stockpiling excess calories and pushing cells and organs to exhaustion.

“The animal data is very striking,” Mattson said. “These aren’t trivial effects on health.”

Of course, many exciting findings that hold true for lab mice don’t translate to more complex human biology. Small, short-term studies in humans do show that periodic fasting reduces weight, abdominal fat, cholesterol, and blood glucose, as well as proteins like C-reactive protein and IGF-1 that are linked to inflammatory diseases and cancer.

But it’s not clear how long these effects last or whether they translate into any lasting clinical advantage — such as fewer heart attacks or longer lifespan.

So some experts say there just isn’t enough clinical data to prove the diet does everything Longo claims. “These are only animal studies. There isn’t a big body of evidence in humans,” said Kristen Gradney, a dietician in Louisiana and a spokeswoman for the Academy of Nutrition and Dietetics. “It could work, but I can’t confidently say that it will.”

“We’re not meant to eat three meals a day — and snacks.”

Mark Mattson, National Institute on Aging

Yet even some scientists who fully understand the limitations of the data are sold.

Satchidananda Panda, a researcher at the Salk Institute for Biological Studies in La Jolla, Calif., compared mice that were allowed to eat whenever they wanted to mice that only had access to food during a 10- to 12-hour period each day. The differences were profound. The mice that fasted intermittently had no gray fur and weren’t lethargic, even as they neared 2 years of age, the average mouse life span.

The results were so striking, Panda and his family have adopted the practice. He also undertakes a water-only fast for a week each year.

“Once you see these animals,” Panda said, “it’s hard not to follow.”

Mattson, too, eats all of his roughly 1,800 calories per day in a six-hour window in the late afternoon and early evening. He hasn’t eaten breakfast in 40 years.

As for Longo, he uses his own diet every few months — especially to lose weight after returning from stays in Italy. Otherwise, he often eats just two meals a day and is passionate about natural, healthy, and plant-based food.

As one of his senior researchers, Sebastian Brandhorst, put it: “Valter always gives us crap when there’s junk food in the lab.”

Longo keeps the mice for his research in plastic bins, some of which are marked “DO NOT FEED.”

‘They thought it was crazy science’

Valter Longo was born to study aging.

Italian by birth, he spent summers in his family’s ancestral home, a town called Molochio in southern Italy that’s home to an unusually high percentage of centenarians. His father is 91. Exactly why the villagers live so long is a question that’s always simmered in the back of Longo’s head.

Now 49, Longo originally came to the U.S. to be a rock star. He enrolled at the University of North Texas, which has an acclaimed jazz guitar program. But he soured on the program when he was forced to run a marching band and turned instead to biochemistry — as a way to study aging.

He moved on to UCLA to pursue a Ph.D. with Dr. Roy Walford, who had become something of a celebrity scientist while pushing the idea that severely restricting caloric intake would extend life.

While he calls Walford a pioneer, Longo soon grew disenchanted with the extreme regimen he espoused. First, it was brutal to maintain. Then, there was what it did physically to Walford, who had been among a Biosphere 2 crew that restricted food intake dramatically during their stay in the experimental habitat. “When they exited Biosphere, they looked liked hell,” Longo said. “Walford looked like a skeleton.”

Walford, a colorful character known for walking across Africa and paying for med school by gaming roulette tables in Reno, Nev., had hoped to live to 120. But he died in 2004 at age 79 of ALS, a disease a number of researchers assert was exacerbated by, or even caused by, his severe diet.

At UCLA, Longo was growing frustrated with Walford’s attempts to study longevity in humans, and even mice, without having adequate tools to drill down into the genetic mechanisms underlying aging. So Longo turned back to biochemistry.

He transferred to a genetics lab focused on yeast, figuring that would let him study the mechanisms of aging in the simplest of organisms.

“If someone said, ‘What are you working on?’ we would say oxidative chemistry. You couldn’t say aging. That was viewed as a joke.”

Valter Longo, University of Southern California

Few people took his early results seriously. Studying aging was still considered flaky. And many scientists at the time were deeply skeptical that you could learn much about human biology by studying simple yeast.

“If someone said, ‘What are you working on?’ we would say oxidative chemistry,” Longo said. “You couldn’t say aging. That was viewed as a joke.”

Convinced his work was important, Longo kept his head down and kept going. “I didn’t pay attention to what people were saying,” he said. In just a year, Longo was able to work out a genetic pathway to describe aging in yeast and show that food — proteins and sugars — could speed aging. It was 1994.

“I was so excited, I thought people were going to say, ‘This is the discovery of the century,’” he recalled. “Of course, it was sent back — rejected.”

Research materials in Longo’s lab.

He rewrote the paper and resubmitted. No luck. He couldn’t get any of the work published without taking out every last reference to aging. The discovery he thought most important — the aging pathway — he published only in his UCLA thesis. “We would get insults from reviewers. The yeast world was the worst. They thought it was crazy science,” he said.

As years passed, other groups started publishing work detailing, as Longo had, specific aging pathways, first in worms and eventually in flies. “The frustrating thing is,” Longo said, “we had all of these things figured out and no one was listening.”

Frank Madeo, a yeast researcher at the University of Graz in Austria, had seen Longo being dismissed at conference after academic conference. Now, he said, the work is finally being embraced. “Valter for sure is a fighter. He doesn’t care what others think,” Madeo said. “He did something that at first was considered weird and he was attacked. Now, it’s the basis of work in so many labs.”

The turning point, Longo said, came when an editor at Science recognized that his rejected paper was part of the new paradigm to understand the genetics of aging. The paper was published in 2001, seven years after he’d first submitted it. It has since been cited hundreds of times.

Once he had the aging pathway worked out, Longo went on to look more deeply at what restricting calories did to yeast cells. He found withholding food “completely reprogrammed” the yeast — cells lived longer and were resistant to threat after threat. “You could throw in any toxin you could think of and it wouldn’t die,” he said.

Fasting “is at the foundation of the body’s ability to protect, repair, and rejuvenate itself,” he said. “We started to wonder: What can we use it for?”

So he started experimenting with limiting rodents’ intake of the proteins and sugars that he’d seen activate the aging pathways. (His lab cooks up a diet by hand for the animals; it’s also the inspiration for the the five-day diet he sells for humans.) His team has found that the diet shows promise in restoring pancreatic cells that keep diabetes in check, boosting immune cells, and helping prevent the deterioration of myelin, which plays a role in multiple sclerosis.

San Diego computational biologist Karmel Allison, who blogs at the diabetes lifestyle site ASweetLife, took a deep dive into Longo’s paper on pancreatic cells and found the data unconvincing. She thinks the improvements in mice could have simply come from their weight loss, not from any cellular change brought on by fasting.

Other scientists agree that’s a key question for further study, in both mice and people. A study published in the Journal of the American Medical Association this May startled some diet researchers by showing alternative day fasting was no better at decreasing cardiovascular health risk factors than normal dieting — and was harder to maintain. (Longo maintains that the popular alternate day and 5:2 diets, where people eat up to 800 calories on their so-called fasting days, are not true fasting, just calorie reduction, and therefore don’t cause the metabolic shifts and cellular improvements of his diet. He thinks at least three days of fasting are needed, though other researchers disagree.)

“In humans, is intermittent fasting only effective for weight loss because we’re restricting calories? In my mind, that’s the big question,” said Grant Tinsley, an assistant professor of kinesiology at Texas Tech University who studies sports nutrition. “Is this just about eating fewer calories or are there unique cellular changes?”

“In humans, is intermittent fasting only effective for weight loss because we’re restricting calories? In my mind, that’s the big question.”

Grant Tinsley, Texas Tech University

Tinsley himself practices intermittent fasting: He restricts himself to eating during a six- to nine-hour period each day or does a 24-hour fast once a week. He likes the idea of Longo’s diet. Yet he’d still like more data. “There really are no side-by-side comparisons of different fasting programs in humans,” he said.

He knows firsthand, though, how hard it would be to conduct such a study. For one thing, it’s hard to get corporate funding for a study involving abstaining from food. For another, human beings are prone to cheat on diets. “Obviously it’s not ethical to keep people in cages for a year and feed them what you want,” he said.

Longo can, however, do that with mice. And he and his lab are excited about new studies showing that fasting seems to strengthen normal cells in rodents while making cancer cells more vulnerable. Longo thinks this means fasting may increase the potency of chemotherapy while reducing its side effects.

And, indeed, small clinical trials in humans have shown patients report less fatigue and fewer gastrointestinal symptoms while fasting during chemotherapy treatments. Longo now has clinical trials underway at several cancer centers worldwide to see if his diet improves outcomes as well.

Longo has found that mice on fasting diets reap a number of health benefits.

A diet that mimics fasting with beets and cider vinegar

Longo came up with the idea for the fasting mimicking diet about 10 years ago. He was trying to test the effect of a water-only diet for cancer patients. But most patients refused to fast and oncologists were worried about their already thin patients participating.

So Longo decided to devise a diet with minimal calories that would provide the nutrition the patients needed, but also confer the benefits of fasting. His lab worked out the precise amounts and types of calories, carbohydrates, proteins, and fats by testing various diets on mice.

The cancer fasting diet amounts to just 200 to 500 calories a day for four days. The ProLon diet allows 1,100 calories the first day and 800 for the next four. (Longo recommends doing the diet under a doctor’s supervision and notes that it’s not appropriate for people with certain health conditions, such as diabetes.)

His diet is low in protein and fat; he gets furious when he sees doctors advocating the opposite, a trendy practice he believes speeds aging.

He gets really fired up when nutritionists call fasting a fad. “Fasting is as old as it gets,” he said, noting that our hunter-gatherer ancestors likely went long stretches between meals. “If 70 percent of America is obese or overweight, you would think they’d have figured out their interventions don’t work.”

“He said, ‘I need to have something that’s going to have almost no calories but still have taste.’ ”

Ambra DiTonno, cafe owner

To devise fasting diets that people would actually want to eat, Longo turned to Ambra Ditonno, a longtime friend who runs a popular Italian cafe in Hollywood.

The two worked together after hours in Ditonno’s panini shop concocting extremely low-calorie soups — some just 30 to 45 calories per serving — out of pumpkin, beets, tomatoes, and broth. “He said, ‘I need to have something that’s going to have almost no calories but still have taste.’ It was really hard,” Ditonno said.

It’s not typical work for a scientist, but was typical for the hands-on Longo, who’s not married, has no children, and is used to working long hours (though he’s prone to pulling out his guitar when asked, and also does a lot of bike riding).

“He doesn’t have any other interests. He’s married to his job,” Ditonno said. And, she added, he had a natural flair for the work: “He’s Italian, so he has some idea of cooking.”

They’d then freeze individual portions of the soups for delivery to cancer patients. (The soups are now manufactured in a facility and freeze-dried so they can be easily shipped and stored.) The diets include additional ingredients — algal oil supplements, specific proteins, trendy additions like flax seed, inulin, glycerol, and cider vinegar — that Longo believes act to improve health or trick the body into thinking it is fasting.

After cooking so many fasting soups, Ditonno tried the diet herself last year. She lost weight, got rid of the extra tummy fat she’d carried since having a child and eased several digestive issues. The benefits have persisted long after that initial fasting period. Like many who work with Longo and have tried the diet, she’s become a convert. “I believe in it like 1,000 percent,” Ditonno said.

The idea of a professor marketing his own longevity diet has raised eyebrows. “It’s a tricky spot to be in,” said Allison Dostal, a registered dietitian and Ph.D. from the University of Minnesota. She was part of a watchdog team that wrote a scathing review of a press release touting one of Longo’s studies that was put out by USC, which also stands to profit if the diet is a financial success. “It’s not something I’ve generally seen.”

The cost of ProLon has also raised questions, especially since there’s no proof this particular combination of foods works better than any other ultra-low-calorie diet or episodic fast.

“The diet’s OK,” Mattson said. “I’m just thinking about the people who can’t afford it. A lot of obese people are of low socioeconomic status. That’s the target population that could really benefit most.”

Longo created a company, L-Nutra, to market the diet, and retains majority ownership. He intends to funnel any personal profits into a nonprofit to fund research. For now, not much money is rolling in, though he says about 5,000 people have used ProLon — some paying customers, some research subjects. He hopes to one day receive FDA approval to market the diet as a tool to help prevent diabetes, but that’s well in the future.

Panda, the Salk Institute researcher, calls Longo’s approach a smart business move.

“The general public wants something encapsulated, they want a prescription,” he said. “Valter’s done a very smart thing. He’s encapsulated fasting.”

Correction: A previous version of this story misstated the location of the University of Graz and Allison Dostal’s academic affiliation.

How Our Medically Supervised ProLon Weight Loss Program Can Deliver the Results You Always Wanted

Here at BioAge Health in Eagan, Minnesota, Dr. Catherine Kodama is passionate about helping each patient reach their optimal health. For many, part of achieving that goal means losing weight.

One exceptional way to lose weight is with intermittent fasting, but many patients find it hard to stick with a fast, even for a short time. That’s why we recommend the ProLon® Fasting Mimicking Diet® (FMD).

With ProLon you can get the weight loss results of fasting, while enjoying their scientifically-based foods that satisfy your need to eat while keeping your body in a state of fasting.

ProLon weight loss program basics

The ProLon FMD is a unique program that gives you the benefit of a five-day fast while still eating healthy, plant-based foods and getting the essential nutrients you need. How can you fast and eat? That’s the genius of ProLon.

When you’re on the diet, you’ll only eat ProLon prepackaged food. Their food is specially formulated to keep you nourished with essential nutrients and satisfied with some food, while putting your body into a fasting state.

The ProLon meal plan was scientifically designed based on research performed at the Longevity Institute and the Diabetes and Obesity Research Institute at the University of Southern California. Then the foods were tested to ensure they would mimic the effect of fasting while providing daily nourishment.

ProLon protocol basics

The ProLong program lasts for five consecutive days in a one-month period. You can repeat the five-day plan every one to six months, depending on your weight loss goals and your overall health. The rest of the time you’ll consume a regular, balanced diet.

The ProLon kit contains five boxes, one for every day of the diet. Inside each box you’ll find all the food, drinks, and supplements you’ll consume that day. The food items include:

  • Breakfast bar
  • Two soups (lunch and dinner)
  • Two snacks
  • Dessert bar
  • Herbal teas
  • NR-1 (vegetable powder with vitamins and minerals)
  • Algal oil (plant-based omega-3)

The types of soups and snacks vary from day to day. Tomato soup, minestrone, and snacks such as kale crackers and olives are just a few examples. For days two through five, your boxes also contain a special glycerol drink for ongoing energy.

The protocol is simple because the ProLon program provides everything you need for five days. The diet rules are straight-forward: only eat what’s in the box for each day in order to achieve the maximum benefits.

Achieving your weight loss goals with ProLon

The ProLon diet is a low-protein, low-carbohydrate meal plan. When your body is deprived of carbs and protein, two things happen that lead to significant weight loss: your body stops converting proteins and carbs into fat, and it begins to burn stored fat for energy.

The extra advantage with ProLon’s food and supplements is that you won’t lose muscle mass. In fact, in clinical trials, ProLon decreased abdominal fat while increasing lean body mass.

Even though you’ll consume the food provided, the ProLon plan is still a low-calorie diet, so you won’t get enough calories to stop fat burning. On the first day you’ll consume about 1,100 calories; after that, each day only delivers 750 calories.

The importance of being medically supervised while on ProLon

Before you start the ProLon diet, it’s essential for Dr. Kodama to screen your medical history, review your overall health, and be sure it’s safe for you to participate in a low-calorie, low-protein, low-carb diet.

For example, you may not be medically cleared to use ProLon if you have diabetes, cardiovascular disease, or some metabolic disorders. You also can’t use the current meal plan if you’re allergic to nuts.

A lab evaluation is recommended in order to evaluate your baseline metabolic state, and follow the improvement from the diet.

After you start the program, we continue to closely supervise your health and progress. When you go on a low-calorie diet, you may experience side effects, so Dr. Kodama is available should you have any questions or need help with physical problems.

When you’re ready to lose weight, you can count on the team at BioAge Health to support your efforts with the ProLon Fasting Mimicking Diet. To learn more about the program, call the office or book an appointment online.

ProLon Review – 14 Things You Need to Know

  • User Comments
  • 10 Answered Questions

ProLon is a 5-day meal program that aims to boost your health with ‘scientifically developed foods’. Its proprietary blend of ingredients claims to put your body in fasting mode, which scientific evidence suggests might be an effective form of weight loss. That being said, this program is not for everyone, and it could be dangerous to people with a low BMI.

Due to its intensity, our research team found that the program has strict guidelines and needs the approval of a medical professional before use. We examined ProLon’s components, side effects, and the testimonials of its users to get to the bottom of this weight loss program. Here’s everything we discovered.

ProLon can be purchased through their .

ProLon Readers: Noom is offering our readers a 14-day trial, for a limited time. for this special offer! Overview

What is the Prolon?

First of all, ProLon is a 5-day meal program designed to nourish the body while “promoting regenerative and rejuvenating changes through scientifically developed, plant based foods.”

Each individual meal comes in its own box- one for each day (around 750 to 1100 calories per day). Inside these boxes you’ll find a cornucopia of healthy, plant-based energy bars, snacks, supplements, beverages, and soups.

After the 5 day period, the dieter is supposed to “transition for 1 day” and then go back to their normal routine.

The website claims that all of their food is scientifically studied and proven to give your body exactly what it needs to be as healthy as it possibly can.

What is a Fasting Mimicking Diet?

This “Fasting Mimicking Diet” also claims that their foods promote positive changes within your body, while making the fasting mimicking period fun and safe for the customer.

We have to say, at first glance, we’re hopping on this wagon – scientific research and natural foods are a pretty good start in our eyes. But if you know us at all, you’ll know we’re not done until we get all the facts.

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×Explanation of Price

This is how much it costs to start on the respective program. We always recommend trying a product before making a large investment.

  • = Initial product cost is less than $5
  • = Initial product cost is between $6 and $50
  • = Initial product cost is between $51 and $150
  • = Initial product cost is $151 or more

The Company Behind ProLon, L-Nutra

The company behind this fasting mimicking diet is called L-Nutra. They are headquartered in California and have been around since 2009.

We scoped out their website and were impressed by the outstanding claims of scientific research and support from the National Institute for Aging and the National Institute of Health.

Apparently, their meal plans emerged after 20 years of research from the University of Southern California. They also claim their preclinical and clinical trials are performed at institutes like the University of Berlin, Mayo Clinic, Leiden University, and University of Genoa.

Scroll below for one of the best products we’ve seen over the last year.


ProLon Ingredients

Since this is a proprietary diet, there’s not a complete list of ingredients. As we do understand this, it leaves a slightly bitter taste in our mouths. We like to know exactly what we’re getting.

We did put in some work and came up with the most detailed ingredient list that we could.

They offer nut bars which list ingredients such as macadamia nut butter, pecan, almond meal, honey, coconut, flaxseed meal, coconut oil, vanilla extract, sea salt, citric acid, ascorbic acid, mixed tocopherol.

Their Kale crackers consist of Golden flax seeds, kale, cashews, sunflower seeds, sesame seeds, nutritional yeast, apple cider vinegar, hemp seeds, dill weed, pumpkin seeds, sea salt, black pepper, and onion powder.

Their drinks contain natural vegetable glycerin, purified water, potassium sorbate, and natural flavor.

They offer a bevy of soups, containing combinations of tomato concentrate, rice flour, potato starch, leek, quinoa, onion, olive oil, parsley, peas, yeast extract, savoy cabbage, carrot, zucchini, garlic, spinach powder, broccoli powder, sage, Champignon mushroom powder, celery, and turmeric.

Their dessert (Choco crisp bar) is made of brown rice, inulin, almonds, almond butter, cocoa powder, brown rice syrup, chocolate chips, rolled oats, rice dextrin, flaxseed oil, salt, and grape juice.

We’ve seen some lists of ingredients that vary slightly from what we came up with, again, this is a proprietary diet and the ingredients aren’t all that certain.


How to Use (Take) Prolon

The healthy diet Prolon and exercise are in collaboration and needs be taken for five back-to-back days, after which the user will progress for a day and after that, resume their ordinary eating routine.

Guidelines and proper instructions are given in each package. A particular blend of nourishment is given on every day for lunch, breakfast supper, etc.

All nutrition given on a particular day must be used that day, as it were.

While a healthy meal missed can be set aside a few minutes during that day, there should to be no trace starting with one day then onto the next.

The 5-day Prolon diet needs to be taken as regularly as is prescribed by the guidelines on the box.

The 5-day Prolon FMD can be purchased from different suppliers. Prolon price range from $200 to $270 depending on your location and distributor.


Prolon Claims

Prolon claims to be the primary Fasting Mimicking Diet that gives you a blend of ingredients and foods ready to reinvent the body into a recovering and restoring mode, bringing about a balance and aging healthy.


Benefits of ProLon

So, what are the benefits of this fasting diet? We’ll list a few for you:

  • Regenerate: ProLon triggers a “natural multi-system regeneration”, which include a variety of benefits from anti-aging and more.
  • Speedy Weight-Loss: No extraordinary claim would be complete without the promise of quick and easy weight-loss. This is exactly what ProLon offers – except they say they have some scientific research to back it up.
  • Convenience: Of course, this diet is as convenient as anything. Each meal comes in its own “grab-and-go” box, making it simple to follow and even easier to access.
  • All-Natural: As we stated earlier, the ingredients and foods in this diet are all-natural; using plant-based ingredients like fruits, nuts, seeds, and veggies.

Side Effects

Potential Prolon Side Effects

In the study and research analysis, most members proclaimed few minor or no unfavorable side effects for the fasting days, although none of these side effects were indicated.

In any case, the organization highlights in a few places on their site that Prolon isn’t for everybody and should just be utilized by adults over age 18, and they should be healthy and strong.

Outside of what’s provided in each box, the organization underlines that no extra multivitamins or supplements must be taken within the fasting or diet period.

Also, unless stated by an authorized doctor, Prolon should never be used with any medications.

Details on Prolon and Weight Loss

The 5:2 diet (in taking just 600-700 calories two days per week) aids with weight loss, and the company claims the body desires to fast for a good long period without eating, so that it goes into safe and secure mode, which is how human beings survived for tens of thousands of years.

The advantages of ensuing a FMD are countless: although weight-loss will unquestionably happen, the key aim is to cover your Life Span-Aging – that is, just how long you live a comfortable and healthy life, before facing any aging disorders.

ProLon Cost

ProLon seems to only be available for purchase on the official website and potentially through your doctor. On the official website, there are three different purchase options.

The first option is for people who want to just try out the weight-loss system. You may buy one or two boxes for $249 each. The second option for purchase is called the “Clinical Trial Protocol” where you can buy three or more boxes sent to you all at once for $225 each. The same price per box is available when you subscribe for automatic shipments.

All shipments on the official Prolon website comes with free shipping.

Where to Buy

The Science of ProLon

If I were writing a book right now it would be called The Science of ProLon, I would apparently have no shortage of scientific studies and research to fill my book to the brim.

The L-Nutra website claims there’s research backing everything – the company even offers relevant science; similar to the research backing the Sirtfood Diet.

It went on to say that 3 cycles of a 5-day fasting mimicking diet were deemed safe and effective.

Remember when ProLon claimed it could help regenerate your body? There is a study with some pretty interesting findings.

Now, we realize that not all of the studies are about this diet specifically, but if you’re anything like us, you seriously appreciate some solid research behind a product’s claims.

Product Warnings

Where to Buy Prolon

Things get a bit tricky when you consider purchasing this diet plan for yourself. You can’t exactly hop on Amazon and purchase this program – you need to pass a test of sorts.

That’s right, there are extraordinary claims and unbelievable scientific backing ProLon. But, not everyone can purchase it – there’s an exclusion criteria. Speak with a physician before starting anything.

After speaking with a doctor, approval for ProLon comes in four ways:

Take a Health Self-Assessment Survey

Take a survey to find out if ProLon mimicking diet is the right choice for you. After taking the survey, it may tell you that you need to speak with a doctor first. If you meet the criteria, the only other step is to schedule a phone call with a dietitian or nurse practitioner.

Health Care Provider Evaluation

You can call the ProLon information line and speak with a professional, or get approval from your own physician.

Use the HCP Code from a Health Care Provider

Once you speak with a doctor, they will provide you with a code. Use this code to finish your registration and to finally order your ProLon.

Doctor’s authorizations and approval codes.

No Medical Conditions

There is an option to check that ensures you have no medical condition or age restriction preventing you from trying Prolon.

Bottom Line

Prolon Product Warnings

Prolon is not considered safe for all dieters. According to the official website and information on fast mimicking diets, individuals should not consume ProLon products if they are:

  • Under 18
  • Sensitive or allergic to soy, nuts, celery, sesame, or oats
  • Pregnant
  • Have different dietary needs that are mismatched with the Prolon meal diet
  • Suffer from any medical condition or sickness
  • Have Body Mass Index (BMI) less than 18
  • Protein-Deficient

When you are following this plan, you should be under the supervision of your doctor the entire time.

“I love fasting and doing juice cleanses, so this was right up my alley. I felt great the entire 5 days, with my most energetic on days 4 and 5. My appetite has actually decreased now that the 5 days are over. I feel as though my body is now in a fat burning mode as I continue to lose weight after the fast. I would highly recommend this to anyone who would like to cleanse at the cellular level as well as the benefit of fat burning and anti aging benefits.”

“I would give it one start out of 5! The food is BAD!! I followed through and lost a few lbs but not worth it!!!!”

“Use real food not packaged food.”

The Bottom Line on ProLon

If you asked yourself, “Is ProLon for me?” you wouldn’t be alone. We’ve noticed a large amount of interest surrounding this diet. There are also bloggers and reviewers chomping at the bit wanting to try it out for themselves. But, we’re just not 100% sure.

Of all the means of losing weight, making lifestyle changes tends to be the most effective. However, long-term lifestyles changes are difficult and can make it hard to stick with a plan. That’s where we found technology picks up offering continuous support.

Among the best weight-loss apps we’ve seen is one called Noom. Noom works with experts and medical doctors to create a platform with personalized meal plans, an extensive food database, real human coaching, and so much more.

Dietspotlight Readers: You can access a 14-day trial today to give Noom a try.

Learn More About Noom “

My Experience with the PROLON Fasting Mimicking Diet

There has been an explosion of research on the fasting mimicking diet (FMD) showing reduced markers of aging, as well as better disease outcomes in diabetes, heart disease and cancer. (1) The Prolon Fasting Mimicking Diet was designed by Dr. Longo, and his company, Prolon, sells a kit with the exact food that was used in his studies.

Before I ask my patients to try something, I feel it’s only fair for me to try it first, so I did! Everything you need is in the box — it contains vitamins and alga oil as well as plant based soups, nut based bars, a coco crisp bar, kale crackers, olives and herbal teas as well as a glycerol drink for Days 2-5. Generally, I don’t eat processed and packaged foods, so this was a big deviation from my normal eating. I’ve done intermittent fasting in the past, so I opted to skip breakfast, and eat only between 11 AM to 7 PM. This isn’t a requirement of their plan, I just thought that it would be easier for me to eat less if I only had to spread my eating across two meals instead of three.

I planned my FMD for a week when my husband was in town for support. I didn’t want to be “hangry” with the kids without another parent to step in and help. Also, we didn’t have any social obligations or plans to dine out. It was terrific to have my kids and husband encouraging me. If your partner thinks you are crazy to do this, try and educate them. There are several online videos with Dr. Longo describing the research behind this diet, which ONLY LASTS 5 DAYS.

Overall, the fast mimicking diet was easier than I thought it would be. I expected to be grouchier than I was. If I felt hungry, I had the glycerol drink and herbal tea. Here are the challenges I experienced:

  1. I cook the meals at my house and it was a drag to make food for everyone and then not be able to eat it.
  2. I don’t tolerate nuts in large quantities, so the nut bars gave me some gas.
  3. I started to feel a little dizzy on the afternoon of the last day, and realized that I had forgotten to have the glycerol drink. Once I drank it, I felt better.

I personally like to cook. Some of my patients don’t, or feel that their lives are too busy. The PROLON FMD is great for folks who need things to be uber-structured and don’t want the hassle of preparing special food and monitoring their fats, carbs and protein. There are online “hacks” for this program using fresh foods that don’t have the backing of Dr. Longo. However, many of them do a good job duplicating the macronutrient distribution in his work. As I like to cook, and feel better eating a few less nuts, I’ll try this next and let you know how it goes.

The FMD protocol was designed for monthly use for three months, then once a quarter. For the next two months I’ll try the program in it’s unofficial fresh foods rendering, and let you know what I ate and how it went.

Oh! Did I lose any weight? Yes. I don’t weigh myself at home, but ended up at my gynecologist on day 4 of the program and had lost 2 lbs since my last visit.

(1) Wei M, Brandhorst S, Shelehchi M, et al. Fasting-mimicking diet and markers/risk factors for aging, diabetes, cancer, and cardiovascular disease. Sci Transl Med 2017;9


I Lost 5lbs of Fat on Prolon’s Fasting Mimicking Diet (FMD)

I first heard about the Fasting Mimicking Diet (FMD) on Kevin Rose’s podcast. He spoke about how his buddy, Mike Maser, CEO of the Zero Fasting App, was diagnosed with Stage 4 non-Hodgins Lymphoma cancer. (Ironically, the diagnosis came after he sold FitStar to Fitbit for $25M.)

Maser came across research by an Italian doctor at the University of Southern California, Dr Valter Longo, that purported that fasting could make chemotherapy more effective with less side effects. He then began the practice of fasting for five days before chemotherapy and believes that it contributed to him being cancer free after just two of his six scheduled rounds of chemotherapy.

The 5-day fast had prepped the bad cancer cells to die, while strengthening the good cells to survive after the chemotherapy.

The Fasting Mimicking Diet (FMD) is a 5 day low calorie diet designed to mimic the effects and generate the benefits of a water-only fast.

Scientifically developed and clinically tested by Dr Valter Longo at the University of Southern California, the FMD is meant to exploit the ability of the body during periods of low calorie intake to enter a protected mode, remove damaged cells and tissues, and undergo self-repair.

Significant benefits were found in yeast and mice during clinical trials:

  • Reduce cancer incidence
  • Prevent bone mineral loss
  • Promote neurogenesis
  • Stimulate stem cell production
  • Protect against chemotoxicity
  • Regenerate beta cells in models of Type 1 and Type 2 diabetes
  • Remyelinate neuron sheaths in models of Multiple Sclerosis
  • Reduced visceral fat stores, which are associated with chronic disease

As for humans, a small clinical trial showed reductions in biomarkers for chronic disease after three cycles of FMD:

  • Lower cholesterol
  • Lower high blood pressure
  • Lower levels of C-reactive protein (inflammation marker)
  • Lower IGF-1 hormone (which fuels the mTOR pro-aging pathway)
  • Reduced visceral fat stores

What is Prolon

Prolon is a 5 day plant-based meal programme developed by Dr Longo. It is a plant-based 5 day meal plan providing 1,150 calories on Day 1 and approximately 800 calories on Day 2-5.

What is in the Prolon Box?

The Prolon daily meal plan consists of a nut bar (for breakfast), two soups for lunch and dinner, and occasionally some kale crackers, olives and a choco bar for dessert. Peppermint and hibiscus teas, and supplement tablets are also included.

The soups for lunch can be microwaved in 2 minutes (convenient for taking to work) but the soups for dinner require stove top cooking for 15 minutes.

Now you may wonder – how is this healthy? It sounds like a lot of packaged food with granola bars and dessert. That’s what I thought initially too.

The plan is well formulated. Honey is used to sweeten the nut bars and the soups are delicious. Dr Valter Longo’s point of view is that high compliance to the diet has far more benefits than the perfectly formulated one (I agree with that!), which is why this diet is designed for compliance as much as it is for health benefits.

How Much Does the Prolon Diet Cost?

One box costs US$249 (includes all meals for 5 days), whereas a set of 3 costs US $225 each (use my coupon code for $20 off). Delivery is free, though shipping internationally may face customs charges.

All plans include an optional complimentary nutrition coaching session with a dietitian or nurse practitioner and there is a wonderful Facebook group called FASTINATION that you can join for support.

Additionally, Dr. Valter Longo, donates 100% of his share of profits back to funding longevity research.

Prolon Review

After reading Dr Long’s book, “The Longevity Diet”, I decided to try the 5 day Prolon along with two other friends during the week of 30 September 2019. At that time, Prolon did not ship directly to Singapore, so a friend carried 9 boxes back from the US!

I enjoyed the week’s fast! I thought the soups and bars were yummy and I loved the teas. I did feel cold throughout the fast but other than that, not super hungry except for Day 3.

D2/D3 I thought I was dropping more hair than usual. Also felt my sweat smelt different. Metallic on D4. Also had big bowel movements on D4 and D5 which surprised me!

I was also slightly intolerant to inulin (the plant-based fibre that is added to the soups) so I was very bloated and kept farting smelly farts on the first 3-4 days but was fine by the last day.

I don’t usually like olives but the ones in the Prolon pack were delicious.

Overall, I loved the experience and hope to continue once every quarter.

Prolon Results

Overall, I lost 1.7kg in weight but 2.5 kg (5.5lbs) in fat which has stayed off even on Day 11, and am extremely happy about that!

In fact, I gained 0.7kg of muscle mass during these five days. (I was working out throughout the fast (note: this is NOT advised by Prolon). However, under my doctor / trainer’s supervision, I decided continued my regular exercise regime which included 90min of yoga daily and 2 weights sessions. I did cut out all cardio.

Visceral fat came down from 5 to 4 (as measured by the Tanita machine at Fitness First).

I also did a blood test at the end of October and saw several biomarkers improve after doing Prolon:

I was extremely happy with these results.

Prolon Tips

If you are thinking of doing Prolon as well, here are some tips and tricks that helped me survive the 5 day Prolon fast.

  1. Go into the diet in ketosis. You’ll be less hungry.
  2. Chop up the olives and throw them into the soup. I also added chilli padi (and next time will chop in some raw garlic). It gives the soups some texture and your teeth something to munch on.
  3. Freeze the Nut Bars and cut them up into cubes if you need snacks throughout the day.
  4. Skip breakfast with a 16:8 or 18:6 fast and you’ll only be slightly hungry in the mornings. I worked out from 7-11am every day so was barely hungry and ate at 12pm and 5pm.
  5. Be careful when microwaving your soups – if it spills over, you’ll have to lick it up. Do the 2 minutes in 1 minute rounds with 30 seconds rest in between
  6. Fuel up with the Nut Bar / Glycerin L-Drink before your workouts to spare lean muscle mass.
    • L-Drink (Glycerin)If you don’t need it, you’ll excrete it in your urine
    • If you need glucose, the body secretes glucagon for gluconeogenesis (when the body breaks down fat or protein for glucose). Glycerol is a natural product when fat is broken down. By giving the body extra glycerol, it spares the body from breaking down lean body mass, so the diet is muscle sparing.
    • This is a key difference between FMD and water only fasts (which tends to result in loss of lean muscle mass)
  7. Shorten your eating window. I would fast till noon and eat dinner at 5pm. This means more food in that 5 hour window
  8. Exercise in the morning. This will help you burn fat and be less hungry.
  9. Make sure you have three full weeks clear to eat clean. Dr Valter Longo recommends that the week before the diet, one should follow a healthy, low protein, preferably vegan diet with limited saturated fat and sugar. Eat two meals a day within a 12 hour window. The week after the FMD is also critical – this is known as the transition week and one needs to eat nutrient dense food to refeed your cells and regenerate your organs (which may shrink during the fast).

Does Prolon ship to Singapore?

Yes they do! After my Prolon experience, I bugged them to start shipping to Singapore until they agreed! Prolon now ships to Australia, Canada, Malaysia, New Zealand, Singapore, South Africa and South Korea. They also ship to Europe (UK, Italy, Spain, Germany, France, Poland, Sweden, Denmark, Finland, Norway and Iceland).

You can order a box from their website for $249 or a set of 3 boxes for $225. Use my coupon code for $20 off, valid for orders from any country).

Bear in mind, SingPost will ask you to pay 7% GST upon delivery.


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