My version of the Fasting Mimicking Diet – by Nils Osmar


Key points:

  1. Fasting Mimicking Diets  (FMDs) are temporary.
  2. They don’t have enough nutrients to support life or health long-range.
  3. No one should try living on one for more than a few days. You’d starve to death if you tried eating one permanently. But they can have profound benefits if done occasionally.

Every now and then I like to do a five-day day fast or a fasting-mimicking diet (FMD).  I’m currently doing one once a month. After trying a number of versions, including the one developed by Dr. Valter Longo and doing some experimenting, I came up with a version of my own which works for me.

I do FMDs partly for weight control. But the main reason I do FMDs is for autophagy and apoptosis, and because of evidence that both fasting and fasting mimicking diets may contribute to a longer lifespan and health span by lowering our mTOR, raising our NAD levels, and clearing senescent cells out of the body and replacing them with new stem cells. FMDs also increase growth hormone in a healthy way while decreasing IGF-1.

Prolon’s Fasting Mimicking Diet

The FMD developed by Dr. Longo and marketed by Prolon has the following elements:

  • On Day 1, those following the diet eat 1090 calories, including 27 grams of protein, 68 grams of fat, and 93 grams of carbohydrates.
  • Over the next few days, it goes down to 725 calories, with 16 grams of protein, 35 grams of fat, and 85 grams of carbohydrates per day.

I tried Longo’s version but found it hard to stay on. It’s high in carbs, which (for me) raises blood glucose and insulin, takes me out of ketosis, and leaves me feeling hungry at the end of the day. 

Most Americans eat hundreds of grams of carbohydrates a day, so for them, it would be a reduction. But for those who’ve eliminated wheat and other grains from their diets, it feels like moving in the wrong direction. So I developed a version that keeps me in ketosis while giving me the benefits of autophagy and apoptosis.

My version: 15 or 16 grams of protein…

  • On Day 1, I eat 27 grams of protein.
  • On the other days, I eat 15 or 16 grams. (The real point of a fasting mimicking diet is to experience both autophagy and apoptosis. Both require that you cut your protein to somewhere in the range of 15 or 16 grams per day (or even less).
  • All protein needs to be from plant sources for the duration of the diet –– no meat, eggs, fish, poultry, or dairy. You should also avoid soy, even fermented soy, when doing the diet.

Why low protein matters

  • Autophagy is a kind of deep cleaning of your cells. Your body needs some fuel, so it scavenges your cells for amino acids it can turn into proteins to keep vital bodily functions going. This accumulated debris out of your cells. It’s similar in a way to taking trash out of your house to be disposed of. Autophagy kicks in when we do without protein for a long enough period of time. See related article
  • Apoptosis is programmed cell death –– in this case the deaths of senescent cells. Around two or three days into a fast, there’s evidence that your body runs out of cellular debris, so it starts eating its own cells. This may sound scary, but it’s good, according to Dr. Valter Longo and Dr. Jason Fung, because the ones it starts cannibalizing are dying/decaying senescent cells. It appears to kick in two or three days after the start of autophagy.
  • Eating more than the allowed 16 grams of protein per day shuts down both autophagy and apoptosis.
  • So, count grams and make sure they don’t exceed 16.
  • I should be clear that I am only talking about how much protein I eat (or limit myself to) when fasting (or doing an FMD). No one should try to live on that little protein indefinitely.  If you try living on a fasting mimicking diet permanently, you’d better have your will made out, because you will die.

50 grams or less of net carbs…

  • After doing several FMDs, I’ve concluded that you do not have to rigidly keep it at 20 grams, which some folks setting up ketogenic versions recommend. You’ll get profound benefits even if you eat up to 50 grams of net carbs per day.
  • To measure net carbs, remember to start with the total carbs than subtract the fiber. It’s indigestible so doesn’t count.

… and around 80 grams of fat

  • What makes an FMD and FMD… what makes it effective… is the low protein. This gives you a little leeway to play with the fats and carbohydrates.  For me, it works bets to set my fats at around 80 grams/day.
  • If you want to go vegan (for the duration of the FMD), good fat sources might include avocados; olives; olive oil, avocado oil; fish oil, krill oil, MCT oil and coconut oil. If you like animal fats, you can add some cream and butter (but no milk).
  • Avoid unhealthy and inflammatory fats like soy, safflower and corn oils. Fats like those found in olive oil and avocado oil appear to be ideal. And some saturated fats (like those found in MCT oil, made from coconuts) can also work well. 
  • Don’t deliberately overdose on fat, just eat a little fat when you’re hungry.


  • Some people doing high fat/low carb FMD diets count calories. But many don’t.
  • For those who want to count them, just follow the guidelines of the Prolon diet. Keep calories to around 1050 calorie total on the first day. Keep them to 750 calories a day or less on the remaining days.

Some of my favorites meals on “my” FMD are: 

  • Lentil soup (a cup of lentil soup seasoned with onions, garlic, cherry tomatoes and parsley… add some olive oil and vinegar for healthy fats and flavoring)
  • Avocados (I had a whole avocado for breakfast one day, on my last FMD; I spiced it up with a little sea salt.)
  • Cauliflower rice with mushrooms
  • A big bowl of peas and carrots and mushrooms with lots of butter and salt
  • A big bowl of veggie soup made with broccoli and cauliflower and mushrooms and onions and kale.
  • I’m not crazy about salads, but if you like them, making a big delicious salad from iceberg lettuce (which has almost no protein), olives, avocados, and cherry tomatoes, makes a great FMD meal.
  • You don’t have to limit quantities, just watch the macronutrients, especially protein. Eat lots of vegetables for a few days, and full-fat salad dressings made from healthy oils.

What not to eat

  • I avoid many of my favorite super-nutritious foods such as sardines, salmon, grass fed ground beef, natto, organ meats, and chicken soup. 
  • I look forward to eating them again at the end of the diet. In fact, I’ll want to eat them at the end of my diet. They’re all high in taurine, a food that you should eat liberally when the FMD is over, because taurine is used in the creation of new stem cells, one of the benefits of an FMD.
  • I avoid sugar and fruit.
  • I take most of my usual supplements, but I avoid astragalus and ashwagandha because they interfere with apoptosis. (They’re good to take for general health, but create problems when you’re doing an FMD.)

Are some FMDs bad?

In my opinion, any so-called FMD that raises your protein above 16 grams is defeating the whole purpose. You’re not mimicking fasting if you’re interfering with the processes that water fasting promotes.

Is my version endorsed by Dr. Longo?

No. His version is very specific. The Prolon diet is a medical diet, which can actually be prescribed by a doctor. My version is just what I’ve come up with that works for me.


You need to watch your PROTEIN and CARBOHYDRATES when doing an FMD, as I mentioned in Part 1. I like to keep my meals simple when I’m doing a fasting mimicking diet because it’s a way of avoiding foods I may be sensitive or mildly allergic to.  So I’ll often have things like a cup of mushrooms or a cup of peas as a meal.

  • AVOCADO – 1 LARGE. Due to their high fat, low protein and low carb profile, avocados are a perfect meal. Add a little salt for electrolytes. Protein: 3 grams. Net carbs: 2. Fat: 23 grams. Calories: 250. One avocado with some sea salt and some low carb green juice is a great fasting mimicking diet meal.
  • PEAS – 1 CUP.  One of my favorite meals when I’m doing an FMD is a big bowl of organic green peas. Add some grass-fed butter and salt for more flavor and for electrolytes. A bowl of peas (with butter and salt) can actually make a very filling, delicious, satisfying meal.  MACROS: Protein: 4 grams. Net carbs: 16 grams.  Fat: 12 grams.  Calories: 118 for the peas alone. 220 calories if you include butter. 
  • BROCCOLI – 2 CUPS. Another filling meal is to cook up two cups of broccoli florets and add some butter and salt. You could just eat one cup, but I like filling up on two. MACROS: Protein: 7 grams. Net carbs: 12 grams. Fat: 12 grams (from the butter). Calories: 110 for the broccoli alone. 213 calories if you include butter.
  • MUSHROOMS – 1 CUP.  Mushrooms are great for anti-aging because they’re full of spermidine. Protein: 2.2 grams. Net carbs: 1.5 grams. Fat: zero. Calories: 16.
  • PICKLES – MACROS: Almost zero carb, zero protein, zero fat. Raw fermented pickles are best.
  • SAUERKRAUT – MACROS: Almost zero carb, zero protein, zero fat. Rich in beneficial probiotics.
  • KIMCHI – 1/2 CUP. Kimchi’s another beneficial food when you’re fasting. The ingredients vary and many people make their own, so these are rough estimates. If you buy commercial kimchi, just trust the label. Make sure it’s raw and fermented. MACROS: Protein: 3 grams. Net carbs: 3. Fat: Zero. Calories: 20.
  • MUNCHIES – If your FMD is going well you’ll probably have little desire to snack. But if you, just try munching on things like celery, carrots, cherry tomatoes and cucumbers. Keep a tray of ’em around to munch on.


  • SPARKLING WATER (unflavored and unsweetened)
  • COFFEE (with or without a little cream)
  • ALOE VERA JUICE (organic inner leaf only; the outer leaf is toxic)
  • Avoid fruit juices, and of course avoid milk, due to its high protein content.


  • BREAKFAST might be a cup of coffee with a tablespoon of heavy cream. (The cream in it is the real “breakfast.”) 
  • LUNCH might be some peas or cauliflower or broccoli sauteed in butter, with some mushrooms on the side.
  • DINNER might be an avocado, or even two avocados if you’re really hungry.
  • Eat within a 12 hour maximum time window. (If you start eating at 7 a.m, take your last bite by 7 p.m. at the latest)
  • I sometimes forget about eating when doing an FMD, which is fine too. You don’t have to force yourself to eat if your hunger goes away. I’ve sometimes started out doing an FMD, then forgotten to eat and ended up doing a water fast instead. But if I’m hungry, the high-fat items listed above will keep me satisfied and full.


I followed Dr. Longo’s diet the first time I tried out an FMD, but found that his was way too high in carbohydrates for me. Also, I’m allergic to some ingredients in the Prolon version.

So the next few times I fasted, I just did water fasts. They went well and were beneficial, but I was seriously wiped out by the end of a five day water fast.

Finally, after some tinkering and some reading to understand the inner workings of the FMD,  I came up with my own version, which has worked well for me, and which I’ve now done several times. 


  1. VERSION 1: The Prolon FMD (a box of food you can buy which exactly matches these macronutrients) (Lasts for five days.) The cost fluctuates, but is around $250/box.
  2. VERSION 2: Eat two avocados and some greens powder every day for 4-5 days (no other food) (plus water and tea) (nothing else) (works but sounds boring to me. And the protein in some greens powders is too high)
  3. VERSION 3: Eat two avocados and a big green salad every day (plus water and tea)
  4. VERSION 4: Eat two avocados and some green juice (such as Uber Greens) every day
  5. VERSION 5: Eat whatever you like as long as it stays within the stated macronutrients
  6. VERSION 6: The ketogenic FMD: This one isn’t quite vegan. Limit your protein and carbs, but not your fat. Some people don’t count calories or grams of fat when doing FMDs. They might drink lots of coffee with heavy cream for a few days, or eat things like celery with cream cheese (being careful to count protein… cream cheese has some… and stay under 15 grams/day). In essence, you’re doing a standard ketogenic diet for a few days, but with almost no protein. (This is essentially what I’m doing on my version.)


  • The FMD is NOT a diet you can follow for the rest of your life. It’s a TEMPORARY diet designed to promote HEALTH AND LONGEVITY. If you did it full time, you would not be getting enough protein to live on, and would starve to death.


  1. Better blood glucose. Lower LDL. Lower triglycerides. Higher HDL.
  2. When fasting or doing an FMD, the body will CLEAN DEBRIS from your cells to make proteins. So you will end up with better functioning cells.
  3. When it runs low on debris, it will CANNIBALIZE SENESCENT CELLS and DAMAGED MITOCHONDRIA. One five-day FMD will clean more than 40 percent of the senescent cells out of the body.
  4. In the five days after the FMD, if you eat a healthy diet, your body will replace the cannibalized cells with NEW STEM CELLS, and trigger MITOCHONDRIAL BIOGENESIS.


THIS WEBSITE describes one approach to creating your own FMD.  The idea is that you could use your own food instead of buying a ProLon box of food, as long as you stay true to these macronutrients.

FASTING has many benefits. Even short INTERMITTENT FASTS (such as skipping breakfast a few days a week, and eating lunch and dinner within an 8 hour period) can support weight loss, lower your LDL and triglyceride levels, raise your HDL levels, and support your mitochondrial health.

PROLONGED FASTS (48 to 96 hours or longer) have the same benefits as the FMD, and can also extend the lifespan, at least in lab animals. (There is speculation that they might do the same in humans, but it would take several human lifespans to verify.) 

There is strong evidence that both fasts and FMDs may help with a variety of health conditions, including some types of cancer and diabetes.


Most people, when they hear the word “fasting,” think of a water fast (drinking only water, and abstaining from food and other drinks for a set period of time).

I’ve done some water fasts, and have benefited from them. But water fasts can be problematic, and some doctors are concerned that they may lead to gradual deficiencies in important micronutrients over time. Plus, they’re difficult for some people to stick with.


Longo’s goal in creating the FMD was to come up with a diet that would provide most or all of the benefits of a prolonged water fast, , while still allowing people to take in some calories and nutrients. (FMD “fasts,” like water fasts, promote autophagy (cleaning debris out of our cells), apoptosis (killing off senescent cells), and stem cell regeneration, which occurs during the re-feed following the end of an extended fast.)

To do the original FMD, you would just order a box from a company called ProLon, then follow the directions. The box includes soups, crackers, nuts and seeds, and other foods. (Dr. Longo helped set up ProLon and design the diet, but he does not profit from or benefit from sales of the product.)

Many people have reported benefits from the doing the ProLon Fasting Mimicking Diet. But some people have shied away from ProLon’s version because of either (1) the cost (it costs hundreds of dollars for the prescribed five days of food), or (2) having allergies to wheat, nuts, soy, seeds, and some other ingredients in the ProLon diet, or (3) already being on ketogenic diets which are much lower in carbohydrates than the ProLon FMD.  (The ProLon FMD is high in carbs and fat, and low in protein.)

So a number of people have looked into the FMD, studying its ingredients and analyzing its macronutrients, to see if they could come up with alternative versions. Some vary significantly from the ProLon diet; others vary just a little. 


The body uses 15 grams a day just to maintain basic body functions such as keeping your heart beating. If you eat under 15 grams, no worries — your body will make its own protein by cleaning out debris in the nucleus of your cells, breaking the debris down into amino acids, then turning them into proteins.

If it runs out of debris, again, no problem — it will start looking for senescent cells to destroy, break down into amino acids, and, again, assemble into new, perfect proteins to maintain body functions.

Of course it can’t do either process forever. You have to eat eventually. Longo recommends doing an FMD once a month if you’re trying to heal a serious health issue, or four times a year for maintenance.


If you’re eating more than 15 grams of protein, your body will NOT go into autophagy, because it has no reason to. (Why bother making proteins, when they’re being provided by the diet?)  (This is why eating collagen or bone broth during a fast would be a bad mistake. More than a bare minimum of protein shuts down autophagy.)

Whatever version of the FMD you follow, if your goal is cleaning out cellular debris and getting rid of senescent cells, YOU MUST NOT EAT MORE THAN 15 GRAMS OF PROTEIN A DAY when fasting or following a five-day FMD diet.



After creating my own version, I did more online research and found out that I was not the first to go there. Nor was my diet unique. One popular version that gives you these exact nutrients is to eat TWO AVOCADOS AND SOME GREENS POWDER every day when fasting. This would give you the exact macronutrients I came up with for my version. fall into the recommended allotment of PROTEIN, but reduce the carbohydrates and increase the fat a little, while keeping the diet ketogenic. 

FAT FASTING: The TWO AVOCADOS AND SOME GREENS POWDER version is similar to an approach called “Fat Fasting” developed years ago by Dr. Robert Atkins, with one exception: fat fasting can involve eating things like egg yolks and fatty meats. These are fine on a normal day of ketogenic eating, but should NOT be eaten during an FMD, as the high protein being consumed will take people out of autophagy and apoptosis. I don’t use it because I don’t like greens powder. But if you do, it’s an easy solution.

If you’re trying one of the variations, or attempting to make up a version your own, remember that whatever other changes you make, if your goals include autophagy and apoptosis (clearing half-dead, toxic senescent cells out of your body), it’s vitally important to keep your protein to 15 grams or less per day.