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.

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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.

Fasting Mimicking Diet Meals

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:
  • Day 1: Total caloric intake of 4.5 to 7 kcal/lb of body weight (10% protein, 56% fat, 34% carbs)
  • Days 2-5: Total caloric intake of 3 to 5 kcal/lb of body weight (9% protein, 44% fat, 47% carbs)

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 macronutrient calculations
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.

Fasting Mimicking Diet Meal Plan

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.”)

Fasting Mimicking Diet Meals
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.

Fasting Mimicking Diet data

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

Fasting Mimicking Diet 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.

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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.

Fasting Mimicking Diet weight and body fat

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.

Fasting Mimicking Diet body fat

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:

  • Start of FMD: Body fat = 23.5% (40.37 lbs), Skeletal muscle mass = 35.2% (60.47 lbs)
  • End of FMD: Body fat = 21.5% (36.16 lbs), Skeletal muscle mass = 36.5% (61.39 lbs)

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.

Fasting Mimicking Diet HRV LFHF

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.

Fasting Mimicking Diet HRV rMSSD

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%).

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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

Fasting Mimicking Diet hs-CRP

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

Fasting Mimicking Diet WBC

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”:

Fasting Mimicking Diet liver markers

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!

Fasting Mimicking Diet Meals

Bonus: Free DIY FMD Spreadsheet

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 monitorSweetBeatHRV 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

About Bob

Bob Troia is a technology entrepreneur and citizen scientist who is focused on the intersection of data-driven citizen science, health and wellness, human performance, longevity, and self-optimization. He has been featured on CBS News Sunday Morning, PBS NewsHour Weekend, National Geographic Explorer, CBC (Canada), SBS-TV (South Korea), Fast Company, Men's Fitness, Outside Magazine, and on many leading health and wellness podcasts.


  1. Avatar
    Kilgore Trout Reply

    I am on my last day of the FMD diet….When I began I weighed 185 now I am down to 180 pounds…first day ate 900 calories, day 2 760 calories, day 3 775 calories, day 4 780 calories, Day 5 750 calories. just 12 g of protein per day, but 60 g of fat and 50 g of carbs.

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    Kilgore Trout Reply

    Today is day 5. Feeling good today, took a 2 mile walk in the park.
    I started at 185 pounds, was 180 lbs this morning at the start of the final day.
    My goal was to stay under 750 calories per day, since my starting weight was 185 and understood you can consume 5 calories per pound which would be 900 calories on days 2-4. Please advise if this is incorrect. Although Day one you can consume more, I stayed below 800 calories on Day one because it was not difficult.

    had avocado every morning for Breakfast, about 10 nuts (macadamia + Almonds) for lunch and cup of veggie soup or Miso soup for Dinner. Also ate 3 mini green peppers yesterday + Today and 1 cup of sliced cabbage with olive oil on day 2 +3. my Protein was kept below 10% of calories, but my fat consumption was over 60% of my calories, with just 30% from Carbs. All 5 days were under 780 calories, averaged about 750 calories per day. First day was easy, second day was the hardest.

      • Avatar
        Kilgore Trout Reply

        yes it was…it really helped my asthma and by the third day my back was feeling better…usually I wake up each morning with a stiff lower back, but the stiffness was gone after 2 days of fasting. The day after ending the fast I weighed just 178 in the morning. I plan on doing this fast every 6 weeks. Next time I will aim to stay below 700 calories on days 2-4.

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    I am on my second find. It is tough. I made the mistake of exercising using the first fmd My wife said I looked drained on the last day. Well burning six hundred calories when you are eating about the same does not work. I am sixty four. Do about ten miles a day on varied terrain on a bike when done and I resumed my normal diet I felt as if I was in my teens. At least in terms of mental alertness and feeling strong Also I noticed greater definition of my muscles one thing I have decided is to let six weeks pass between fmd it is a tough regime although I think it is benificial. Would like to know if it is having the desired effects in my stem cells. I also take an extract of Japanese knotweed that probably contains at least fifty percent resveratrol. I also take piperin with it which increases the serum levels of resveratrol 2x and the time in the blood from thirty minutes to three and a half hours. I have been doing this since 2006. When I added the piperin a significant amount of hair grew back on my head and that hair grew in dark rather than with grey. Feel free to ask me questions

    • Avatar
      Rob philip Reply

      Clearly I’m late reading this, but I’m interested in your Japanese knotweed extract and piperin. Any chance you could point me at the research and possibly source for the two?

      • Avatar

        Pipeline is biopiperin at Swanson’s Vitamins and go to acupuncture Atlanta and look up by zhang. Oddly enough. The cheaper bottle is subjectively the superior. Where can I get this evaluated or an accurate csa? I have Another formulation that distinctly has
        Positive affects on memory. Perhaps we could talk. Alex Mark.

        • Avatar
          Rob philip Reply

          I did some research since posting that message to you. I did, in fact, buy biopiperin at Vitamin Cottage, along with 30 days worth of 250mg resveratrol capsules. We’ll see what effects the two have. Much as I hate shaving I stopped wearing a beard as it got grey. Perhaps I’ll enjoy similar results as you.. How long did it take before you noticed a result. I know it was 12 years ago, but hey – you’re doing something for memory so maybe you recall. 🙂

          What is it that you’re doing for memory? Feel free to email me on – I’m rob.philip

          Also, FWIW I’m not personally convinced that a FMD is better than a water fast. Despite the clenching of teeth and wringing of hands by other people, I don’t find it even a little bit difficult to water fast. I’ve done 6 days (October) 5 days (November) and I’m on day 4 now in December. I feel amazingly good today – nothing resembling hunger at all. Many many FMD journals or youtube videos I read or watch the person doing it complains a lot about being hungry, having a headache, low energy, etc.. when I water fast I am hungry on day 2, aware of my stomach on day 3 but not explicitly hungry and totally normal (not at all hungry) on day 4 and beyond. I think I’ll just do water fasts… 🙂

          • Avatar

            Thats my experience also. I have water fasted for up to seven days, and it gets easier with each day which is a little creepy. I feel a really strong burst of almost manic energy every morning, and then a dead time in the afternoon when I like to nap if I can. The highs in the morning must be from releasing ketones overnight. I drink only black coffee and water. After the refeeding period a week after after my seven day fast my HDL was up 50% from normal levels for me.

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    Bob – Ive read Damiens blog on using 2 avocados and appears you have a modified version of it, but what are your thoughts on the macro ratios based on simply 2 avocados and his greens supplement? The ratios dont appear to gel with the official FMD diet. Is that why you modified yours? Thanks

  5. Avatar
    Alok Chopra Reply

    How many meals a day does this diet have to be distributed
    Can eggs be eaten
    How much and what type of meats are included

  6. Avatar
    Alok Chopra Reply

    How much excercise is allowed
    How many meals
    Eggs ?
    How much meats

  7. Avatar
    Victoria Rodriguez Reply

    I’m on day 5 of the FMD with a diet set up by my Endocrinologist and nutritionist and am rather disappointed. I have lost close to 5 pounds in the first two day and seem to be gaining 1/2 pound each subsequent day. I have a number of chronic diseases (PCOS, T2 Diabetes, and Hashimoto’s) which is why my PCP/Endo recommended trying this. I have had the weirdest responses. I have been in pain and discomfort the whole time. I moved on from hunger pains to a constant state of nausea since mid-afternoon on day 1, I have had periodic cramps all over my body, my glucose only goes below 90 mg/dl in the afternoons but immediately spikes over 160 after every meal or snack, and my fasting numbers have not lowered, they seem to be getting higher. I am supposed to get a blood test tomorrow but am not sure if I can do this for another 2 months (going through the 5:25 day cycle). It isn’t the psychological aspect, I can endure anything if it will get me the health results I need, but this does not seem to be a case where it would benefit the majority of people with diabetes as it is being purported to be. I feel that more testing and data is required, and not just with pancreas samples or a small sample size of humans.

    • Avatar
      karen knight Reply

      You tried once. Of course you will be releasing toxins during your first fast.

  8. Avatar
    Kathy Cook Reply

    Wondering how your bowels reacted to the 5 day mimicking fast? On a water fast it was always important to detox through the kidneys and bowels. Did you add anything for this aspect of the 5 days? Thx

    • Avatar

      No, I didn’t experience any bowel issues such as constipation. I mentioned in my post that I did experience some kidney pain around day 4, so would add in some support such as milk thistle.

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    Hi Bob
    how many times did you eat? did you limit your caloric intake in 2-3 meals or throughout the day? did you allow a certain number of non eating hours?. thanks Marcy

    • Avatar

      Hi Marcy, everything is outlined in my post. I split my caloric intake between AM and PM “meals”.

  10. Avatar
    Joe Antenucci Reply

    Hey Bob, this is an incredible fasting resource! I’ve been googling this FMD for a few days and listening to Longo’s interviews, this is best how-to guide out there on FMD without buying a $250 box. Thanks so much for putting this all together!

  11. Avatar
    Kaan Kocturk Reply

    Hello Bob,
    So 2 questions
    1- How do you officially start the fast? Do you eat normally one day and the next you begin?
    2- Are 2 avocados per day (and greens powder) as efficient as prolon for days 2-5? If so, what should I eat on day 1 assuming I’m doing the avocados for the rest?
    I’m just an average guy 178cm 72kg.
    Thanks a lot!!

    • Avatar

      Hi Kaan! Correct, to begin simply eat as you normally would until you start day1. I was simply attempting get a close approximation of the original FMD studies. Prolon is always going to be better as it’s created by the same researchers, and they probably continue to make tweaks. It simply comes down to convenience, budget, and whether you require medical supervision. Good luck!

  12. Avatar

    Hey Bob, I feel sorry I only bumped into your article after I purchased the ProLon, I’m on my 4th day I’ve been measuring my ketones and I never got anything over 0.9 and there were times after some meals where it have dropped to 0.4, when I did water fasting I could only do it for 3 days never manage to go more than that…, but my Ketone levels were up to 8 and never less then 2. I thought the FMD would offer me something similar, with the advantage to help me to make it last longer. But the ProLon program, is the same amount of calories no matter what, the only variable is a “glicerine” liquid, that it is adjusted to your weight. So now I can only hope that the “science” behind it has a meaning I can’t really understand and all the great things it does propose are happening now.
    But the take home is, what ever it is I don’t think is strongly related to ketone bodies.

  13. Avatar

    Hi Bob,

    Thank you for this very helpful resource. I have used it, along with other material, to create my own FMD programme, following all the nutritional guidelines. I am on Day 4 and the only thing I am really measuring through the five days is my fasting glucose in the morning. Sadly, there seems to be no change at all. The readings oscillate between 100 and 120, like they did before I started. I am a severe case of Polycystic Ovarian Syndrome and Insulin Resistance and was hoping something would budge. I will repeat some of my bloodwork after the five days to check on lipids and inflammation. I am committed to doing this, but I am wondering why it has not had the drastic positive results it has had for everyone else who has tried it. I had about 1020 cals the first day and under 700 for the rest of them – all plant and nut based. I know this might not be enough information but I’d like to hear your thoughts. Thank you!

    • Avatar

      Sorry if you are already aware of this, but glucose levels will typically rise for 1 hour after waking up (for those with insulin resistance this is often referred to as “dawn phenomenon”). And yes, underlying inflammation/stress could possibly be linked to elevated glucose levels. If you aren’t seeing any positive changes in your bloodwork you may want to connect with a practitioner to dig deeper (since I am not a doctor). Good luck!

      • Avatar

        Thank you Bob. Got my bloodwork back. I have seen a reduction in my hs-CRP and Triglycerides, which is good. Other markers remain the same, while Cortisol has risen. Yes, I am aware of DP and I guess that explains it. And many years of IR cannot be reversed with a single cycle. Even so, I do plan to repeat the FMD in the coming months. Your article has been so critical in understanding it and arriving at my own version. Am grateful. There’s really no practitioner to turn to in my context. Let alone help, most people have not even heard of this research 🙂 So I might keep coming back here.

  14. Avatar

    Hi Bob, great resource! I didn’t see where or if you mentioned what you ate immediately after the 5 days. I was reading “The Longevity Diet” and he mentions day six should be high in complex carbs and one should avoid fish. Do you happen to know the reason for this? Thanks

    • Avatar

      Hi Nate! They recommend a transition day (day 6) to allow your body to re-adapt to eating larger quantities of (easy to digest) foods such as soups, smoothies, and salads along with slow-digesting carbs for some fiber. I believe they recommend avoiding both fish and meat that day. Personally, I did not incorporate a transition day as they outlined (some people are ok without it), but my first meal was on the smaller side (omelette, potatoes), and did have some animal protein that evening for dinner.

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    Dawn Parkin Hames Reply

    Hi Bob, thanks a million for sharing and all the science. I am on Day 5, and so far I have lost the same amount of weight as you have on each of the days, even though I am female and weight more than you. It was actually a way better experience than I thought it would be. I did a lot of physical labor on Day one at work unfortunately, and the muscle repair took longer than usual. Tired by early evening of Day 2. The rest of the days my energy has been good. I have went to bed a little hungry every night, so it has been harder to fall asleep, but I sleep a little better than usual. In the morning I was able to make it until 11:00 or 12:00 noon before eating. On day 4, I got cold hands like you did , in the evening for about an half hour. I just felt cold all over, I wrapped in a blanket and it quickly passed. I find when I eat now I get hot. I never had body heat from eating before. I am also tracking my measurements, and I have lost 3/4 of an inch off my waist, 1 and 1/8 inch under the bust, 2 inches off my bust, 2 inches off my belly , 1/4 inch off my hips, 1/8 inch off my thighs, 5/8 inch off my calf, and 3/8 inch off my upper arm. I added a prebiotic fiber supplement to my morning decaf coffee to help with the detox and it seems to work. It is prebiothrive from GundryMD. I also take a probiotic to help the gut microbiome. I have tracked my macro with a excel spreadsheet, I am eating salads based on arugula and non starchy vegetables or zucchini with non starchy vegetables and avocado. I have also had cook greens with butter, salt and pepper. I did an awesome smoothie with 1/2 avocado, 1/2 cup blueberries, 1/2 cup coconut milk 1 cup water and some ice cubes. I am not sure if blueberries are allowed on the FMD, but if was an amazing treat, and it fell within the percentages of the macros. I am testing for ketones with ketosticks. I went into mild ketosis after the first day, and the ketosis increased to in between moderate and high on day 4 and back to moderate on day 5. Perhaps the blueberries dropped it back a bit. I am wondering how much weight came back, and what you think about blueberries? Thanks again

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      Hi Dawn! Glad to hear about your progress. Regarding blueberries (the smoothie sounds great), as long as you are staying within your calculated macros/nutrients you should be fine (personally, I prefer to go with food items that are the most “filling” – i.e., raw cauliflower, etc.). I can’t speak to the weight concern (one should not really be gaining weight during a fast unless they are retaining water/constipated/etc.) because as I mentioned in my post I do not do FMD for losing weight but rather for the regenerative benefits. Thanks!

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      I went with sweet potatoes because they were cheap, convenient and got me to my target nutritional numbers.

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    I know this is an old post but it’s really interesting and I wonder if there’s anyone reading now who might be able to advise me? I had a prediabetes diagnosis 2 months ago (HbA1c 6.1%, 43 mmol/mol), a big surprise as I had a BMI of 19.1, had been doing 5:2 intermittent fasting for 4 years, was physically active several times a week, including HIIT, and ate healthily. I researched and decided to go LCHF and up the exercise even more. 2 months on, I have lost about 6lb, BMI now 18.4 and blood sugar still not reading in the normal UK range (below 5.5mmol/l), still mostly in the 6s. I’m not sure what else I can do so am wondering about the FMD. I wonder if anyone has been in a similar position and can advise whether a few rounds of this might show an effect on BS? Thanks in advance.

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      I am a health coach that that specializes in blood sugar balancing. I had a client in the past that i suspected had Latent Autoimmune Diabetes. Not knowing what you are actually eating, this is just a suggestion.

      The othe thing to consider is that our blood sugars all respond differently to foods. So best to overtest to find out what foods are elevating your blood sugars. I have my clients test right before they eat, right after, every 15 min for an hour and then every hour until they eat again. Any food that raises your blood sugar more than 10 points or above 110 should be avoided. When I tested mine I had some surprises. foods that don’t raise other people’s were raising mine.
      So that might be an issue as well.
      Here is some more informaition on Latent Autoimmune Diabetes –

      I hope that helps

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    Tanya Grimes Reply

    Hi…great information!! Would you please post your current meal plan and information? It’s been over a year since posting this …I am sure you have perfected things and I would love to see and learn 🙂

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    Dalila Robin Reply

    I was looking for a way to reduce my high blood sugar naturally … Today is “Day 1.” Wish me success!

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    thank you very much for all those information. It would be very interesting to read about the results of your next FMD (s). I already tried water diet but it was so difficult ! i will start FMD with you indications this wkd. Merci

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    Shannon’sFrozenPeas Reply

    Very interesting, thanks for sharing. I didn’t realize you were supposed to limit activity.

    I did read that you’re supposed to limit it to ‘zero to 1 coffee per day’ so was surprised to read you had 2 a day. Seems like that would effect your adrenals, etc. He also said to eat olives and nuts.
    This sounds difficult! Did you feel hungry often? Can you have unlimited broth?
    Thanks again

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      Just to clarify, I never stated activity should be limited – I personally chose to refrain as I did not want that to affect my data. I do know some people who are able to light physical exercise, some who try to train a bit harder, and some who refrain from doing any exercise.

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    Hi Bob,

    Thank you so much for this information. I’m about to start the FMD, on Sunday. Can you please tell me the math formula for converting the known percentages of fat, carbs, and protein into actual grams? I have no idea how to do this!

    Thank you

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      Hi Cindy! It’s all calculated in the spreadsheet I provide in the post. As a rule of thumb, 1g of fat is 9 calories, 1g of protein is 4 calories, and 1g carbohydrates are roughly 4 calories.

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    Just to say it is a lot easier than the bone broth fast recommended by Jason Fung. I tend to do the 5 day version. The hard bit is not hunger, but “taste” boredom, which FMD avoids. My wife can’t do a bone broth fast, but is finds FMD OK. Unsure as to why exercise isn’t recommended. I keep exercising as usual with no ill effects. Last point on losing muscle; Jason Fund and others say that whilst some might be burnt during fasting it comes back strongly with referring at the end of the fast. A good link is

    Like all the info. Very helpful!

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      Thanks! I agree with Dr. Jason Fung regarding the mechanisms of fasting, increase of growth factors and minimal loss of muscle (since it can turn fatty acids into glucose) as well as the growth factors increase upon refeed (look at my testosterone after I refed).

      Just to clarify, I never stated activity should be limited – I personally chose to refrain as I did not want that to affect my data. I do know some people who are able to light physical exercise, some who try to train a bit harder, and some who refrain from doing any exercise.

      I just completed a 3 day water only fast and I exercised 2 of the days and felt fine (I mainly did it to use up my glycogen stores faster).

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    Stephen Sheldon Reply

    I had a similar experience with the FMD I did not quantify as much is you even though I am a medically trained person (veterinarian). Losses in body weight and fat composition were almost identical to yours, we are both the same size. I was able to train, Im a bike rider:racer at low intensity. Something I did quantify is my rides and two days after the FMD I had hands-down going away the best cardiovascular and power output performances I’ve had in two years and saw maximum heart rate 5 bests/min higher than I have seen in over five years There is no doubt that it recharge my cardiovascular and aerobic systems. Bought the diet but will make my own the next round, plan on doing it again in a month

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      Hey Stephen! That’s awesome – were you measuring ketones? A lot of competitive cyclists are now taking exogenous ketone esters during competitions for this very reason (also, it’s 100% legal!)

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    Geraldine McMiller Reply

    Hi Bob,

    I’m doing Dr. Longo’s program (currently on day 4), but was looking for recipe’s where I could DIY for next time. The Prolon kit comes with a proprietary glycerol drink. I believe the purpose is to keep you hydrated. Did you hack that part of the program as well? If so, what did you use?

    Excellent article, btw! Thanks for posting/sharing!

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      Congrats! Hope it is going (or went) well. No, I simply ensured that I had some salt and micronutrients (and plenty of quality water!) to maintain electrolyte balance and hydration.

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    Barbara Bearden Reply

    Great info & read! Dr. Bill Cole suggested I try the FMD, I have hypothyroidism & I’m having difficulty losing weight, etc. Where can I get the recipes you spoke of?

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