Prolon’s 5 Day Fasting-Mimicking Diet

 In Blog, Diet, Health

This is a guest post from Wahls Protocol Health Practitioner, Kristen Ude, DC, CCN

“A little starvation can really do more for the average sick man than can the best medicines and the best doctors.”  -Mark Twain (1835-1910)

For many struggling with long-term autoimmune disease, there are not a lot of “short-cuts” or “quick and easy” ways to reverse inflammation, slow down disease progression or just get a temporary break from discomfort.  The Wahls diet, building resilience to stress, and deep, restorative sleep all work together to potentially slow down and reverse disease progression (this is the hope for all of us), but as many of us can attest, this work is multi-factorial, slow and interwoven.  

I have seen good success with supervised, modified fasting programs such as The Optimum Health Institute (in San Diego, CA and Austin, TX).  They do not claim to offer fasting, but rather a detoxifying, whole food, raw diet with colon hydrotherapy and an environment that promotes healing on mind, body and spirit levels.  However, I call it modified fasting because you’re basically eating between 500-1,000 calories per day. While their program (based on ideas by Ann Wigmore) emphasizes raw enzymes, sprouts, wheatgrass, and colon detoxification, today’s parlance would be that you are getting your insulin receptors reset (no sugar whatsoever), a new microbiome (fiber-rich vegetables for every meal) and you are benefiting from the body’s natural and ancient response to fasting (inhibition of MTOR signaling pathway which confers protection against many diseases).

While I greatly appreciate the Optimum Health Institute as a trusted facility to return to when I need deep rest and a full-body re-set, it does require you take a full week off work and costs around $2,000.  However, do check it out if you or a loved one is facing a serious health challenge.

For the purposes of this article, I will return to what people can do at home. 

I know many people successfully incorporate all kinds of fasting regimes into their lifestyle now, but there is some research that suggests if you routinely compress your eating into a 6-8 hour window, your risk for gall stones increases (I have seen it happen).  Other problems that can arise are related to the adrenal glands and blood sugar regulation.

If only we could snap our fingers and get into ketosis, clean up decrepit, old cells, replenish fresh stem cells, maintain muscle, do a major re-set to modulate the immune system  AND NOT STARVE!

Well, I’ve got good news.  What I’m about to explain is the most promising (and do-able) thing I’ve seen in 25 years of indefatigable research and experimentation toward trying to put difficult autoimmunity into remission.   

The Fast Mimicking Diet is a program developed by USC Professor Valter Longo, Ph.D. who Time Magazine calls “One of the most influential people in healthcare” for 2018.  He is the director of the USC Longevity Institute and has dedicated his life to understanding how to age well with an increased “health span” (long and healthy until the end).  

At its core, the 5 Day Fasting Mimicking Diet by ProLon (at least 60% of all sales go back into research) is a large white box that arrives at your doorstep.  Inside, you will find 5 smaller boxes that contain all the food you will need for this five-day fasting-mimicking re-set.  

First, let’s get the contraindications out of the way.  This 5-day fasting-mimicking diet may not be appropriate: 

  • If you have a history of an eating disorder such as anorexia or bulimia 
  • If you have an extremely low BMI (see chart on for exact heights and weight, but for example, it’s not for you if you are 5’7” and under 115lb)
  • If you have a severe allergy to nuts, tomato, honey, oats, sesame or celery.  This program is gluten-free, dairy-free and soy-free, but most in this community should check the website for exact ingredients.  There are a few tiny legumes in the dried soups, potato flakes, and things that aren’t typically part of the Wahls Protocol. Currently, they are including 3 full tomato soups in the 5-day program, but if you comment at checkout, they are willing to swap the 3 tomato soups with mushroom or veg or quinoa veg minestrone.  Many in this community also don’t eat a lot of nuts, but with the overall small amount of food consumed, I find that the nutbar each day is OK for most as long as there is not a frank nut allergy. This particular program is definitely not for you, however, if you have an anaphylactic allergy to nuts. Also, the few tiny legumes in the soup are negligible as long as you’re not strongly allergic.  
  • If you are pregnant, considering becoming pregnant or breastfeeding
  • If you are less than 18 yo or over 70 yo (need doctor’s consent)
  • If you have fever, diarrhea, cough or signs of active infection
  • If you have a history of fainting (syncope), you will need to be very careful

This program may be right for you:

  • If you carry at least 10lb extra weight most of the time, particularly around the belly (this usually indicates some level of insulin resistance)
  • If you have any precursors to cardiovascular disease.  Fasting seems to lower LDL and triglycerides.
  • If you are overweight or obese (also see The Obesity Code by Jason Fung, MD who specializes in fasting in his Intensive Dietary Management Programs for diabetes)
  • If you are relatively healthy without a lot of prescription medications
  • If you have higher than normal levels of inflammation and/or neurological problems either from a defined autoimmune disease, multiple sclerosis or an undefined condition.

If you are taking medications, say for autoimmunity or heart disease or diabetes, this program can still help you, but you need to discuss it with your doctor and check out the on-going research on your particular condition.

Just as an observation, I have seen people with Hashimoto’s (autoimmune hypothyroid) who have been stable on a certain dose of thyroid medication for years need to reduce their dose of thyroid after the fast.  With your prescribing MD’s permission, you may want to consider lowering thyroid medication during the five days of the fast. Conversely, you may maintain on the same level of drug, carefully monitor your symptoms (signs of being overmedicated with thyroid include rapid heartbeat, anxiety, sweating, restlessness).  If you plan to do a few rounds of the fast, say spaced out every 2 or 3 months, you may be surprised when you do your next routine thyroid bloodwork. Perhaps your thyroid function actually improves and you will need less medication. This is something that is not yet clear in the research, but simply what I have observed and what may need attention from the prescribing doctor.  

Many people will ask, “Can I still work while on this 5 day fast mimicking diet?”  Ideally, you chose five days which will allow for more rest than usual. The first day is not too difficult because you are given food that equates to about 1,200 calories.  You may wish to start on a Friday. Days 2-5 are closer to 800 calories each. Most people feel some fatigue and slight discomfort from hunger on days 2 and 3 and these are the days that I recommend people have the option to nap frequently throughout the day.  You may want to start a good book or write in a journal and take short, gentle walks outside, letting your bare feet ground to the grass. On one hand, it’s good to have a distraction so you don’t over-think the hunger, on the other hand, you do not want something that will require major brainpower days 2 and 3 because this is the autophagy/clean-up phase of the fast.  However, days 4 and 5 usually deliver you to the stem cell phase where you feel gifted with superior brainpower. You may be able to play a difficult piece on the piano or solve a complex problem that has stumped you for years. The brain becomes revived.

As described on the website, the days shake out like this:

Day 1: The body begins to transition to a fasting state so it can begin cellular recycling.

Day 2:  The food in Day 2 guides your body to switch to a fat-burning state.  Cellular clean-up (autophagy, which translates into “self” “eating”) begins.

Day 3:  Continued cellular recycling (taking out the trash, breaking down old, damaged mitochondria, dis-assembling mutated cells that were headed for trouble).  Many people on Day 3 will reach the fat-burning metabolic state known as ketosis. The brain does exceptionally well when the fuel source is switched from carbohydrates to ketone bodies and this often happens now.

Day 4:  Autophagy (cellular clean up) continues and stem cell-based regeneration is ramping up.  This is starting to feel really good for most people. Belly fat is targeted as the body is burning visceral fat preferentially now.

Day 5:  Rejuvenation continues from within while greater and greater numbers of stem cells find their way to replacing your weakest links.  After you have a done a couple of rounds of the 5 day fast mimicking diet (perhaps a couple of months apart), Day 5 is an easy day and if you have more than 10-20lb of extra fat, you may go another couple of days in a similar eating fashion to take advantage of the ketosis.

Day 6 and returning to food:  This is when the magic happens.  This part can not be forgotten as long-term fasting without re-feeding can lead to…well… death.  In the re-feeding, you slowly come back (in this community) to your Wahls Protocol. It is recommended that for days 6 and 7 you do not eat steak and you continue with soups and smaller amounts of food as your stomach will have shrunk.  In The Longevity Diet by Dr. Longo, he recommends a base diet that is lower in protein and much higher in complex carbs than the Wahls Diet.  In fact, he recommends cereal, bread, and pasta in moderation, which we know can cause intestinal permeability in our community of autoimmune people.  He is also from Italy, where the food has not been adulterated and sprayed with pesticide as in the U.S. Therefore, I recommend you take the follow-up diet recommendations with a grain of salt and stick with what Dr. Wahls has laid out for us in the special case of immune-mediated inflammatory diseases.

In summary, people with chronic inflammation and/or neurological challenges can help accelerate autophagy (aka housecleaning/removal of damaged mitochondria) when given a break from the daily digestion of regular meals.  This program works like a symphony to re-modulate the microbial population in the gut which then opens up fresh lines of communication with the endocrine, nervous and immune systems.  

Personally, I have completed three rounds of Prolon’s FMD over the course of 7 months and each one has brought me to a higher level of wellness.  I admit I have been trying to follow what we now call an autoimmune paleo diet since 1995 (shout out to Dr. Datis Kharrazian and many forward-thinking chiropractors of the 1990’s), but it’s never been easy.  These cycles of fasting (as well as my annual trips to Optimum Health Institute and the Wahls Protocol seminars in the summer) seem to have truly caused an intrinsic behavior conversion where I am more consistently choosing Wahls-type foods and less interested in the foods that cause intestinal permeability, inflammation and feed the bad bugs.  Sometimes we stubbornly want what we want (like on a good day, at a social occasion), but I for one am grateful there seems to be a visceral understanding of what kind of response a food will have in my body before I bring it to my lips.

Wherever you are on your journey, keep going.  Love and bless yourself. This is a difficult hand of cards we have been dealt and I hope that this information helps someone take their next step toward remission.

For more information, see

The Longevity Diet by Valter Longo, Ph.D.

The Complete Guide to Fasting by Jason Fung, M.D.  

Documentaries (available on youtube):  Fasting and The Science of Fasting

Mark Hyman, MD’s podcast the Doctor’s Farmacy with Valter Longo, Ph.D.

Disclaimer:  The ingredients in ProLon are considered generally recognized as safe (GRAS).  ProLon is not intended to diagnose, treat, cure or prevent any diseases and has not been evaluated as such by the FDA.

Written by Kristen Ude, DC, CCN

Dr. Ude is a chiropractor, certified clinical nutritionist and Wahls certified practitioner in Austin, TX.  She has studied autoimmune conditions and their varied causes since 1994. Priorities in healing frequently relate to stress, structure, toxins and nutrition.  She can be found at

Recent Posts

Start typing and press Enter to search