I Tried a Fasting Mimicking Diet

Fasting has profound health benefits but who wants to go days without eating?! Introducing the Fasting Mimicking Diet — a novel approach to promoting longevity.

prolon fasting mimicking diet

If you follow me on Instagram, you know that last week I embarked on something a little out of the box.

I tried the “Fasting Mimicking Diet.”

FYI – I was NOT paid to do this.

I was afraid when I shared what I was up to that some would think I’d fallen victim to one of the many fad diets out there.

Let me tell you — the Fasting Mimicking Diet is not a trendy weight loss diet, or a cleanse, or like anything you’ve ever heard of before. Its premise is supported by research from all over the world with potentially life-changing benefits.

It is so much bigger than weight loss. It is about longevity.

It is about matching your healthspan (years lived free from disease) to your lifespan.

healthspan vs. lifespan and fasting mimicking diets

Yes, you will likely lose some body fat, but to call it a weight loss diet is to miss the point entirely.

Dr. Valter Longo + The USC Longevity Institute

I first heard the term “fasting mimicking diet” while taking a course on genes and longevity with Dr. Valter Longo in Italy last summer as a part of my dietetics program.

Longo is a biogerontologist with decades of research under his belt and is credited with helping discover pathways in cells that regulate aging. He is the Director of the Longevity Institute at the University of Southern California and is, in no better words, a rock star in the field of aging.

Still, like many of you I’m sure, my first thought was, “What is this nonsense?”

After listening to Longo lecture passionately, authoritatively, and at many times way over my head, about the colossal amount of research supporting fasting for health and longevity, and inundating our class with a mountain of peer-reviewed studies, I quickly learned that this so-called “diet” was anything but nonsense.

My mind was blown.

The Science Behind Fasting

In short, fasting and caloric restriction have both shown to significantly extend lifespan and prevent or reduce chronic disease in many organisms by activating pathways that put cells in a “protective mode” in which stress resistance, DNA repair, and autophagy (when cells “self-digest” dysfunctional components) are increased (1).

It’s fascinating. Basically, cells respond to the stress of fasting by becoming stronger!

nutrient sensing pathways and fasting mimicking diets

In mice, caloric restriction can extend lifespan by 50% (1).

Can you imagine the average person living to 120 instead of 80?

However, a lifetime of caloric restriction would not only be impossible (and totally miserable) for most people, it could also be harmful, potentially causing reduced immunity, poor wound healing, and decreased reproductive function(1).

That’s where fasting comes in. Fasting achieves many of the benefits of caloric restriction but without the adverse side effects.

As opposed to chronically restricting calories, with fasting the period of restriction is followed by a return to a normal diet. And in fact, this “refeeding” period is actually just as important as the fast. It’s during this time that cellular regeneration occurs (2). In mammals, fasting produces a coordinated, system-wide major reduction of white blood cells, which is followed by regeneration of hematopoietic stem cells (2).

Stem cells give rise to all other cells in the body — red blood cells (energy production), white blood cells (immune system), and platelets (blood clotting). They are important for replacing old, damaged cells and regenerating tissue, and their production decreases with age. Some experts believe that the reason we age is due to a decrease in the regenerative capacity of these cells, which leads to chronic disease.

So, the ability to regenerate stem cells through fasting is pretty remarkable. However, straight water fasting can be dangerous and pretty unbearable for the majority of people.

That’s why Longo and his team starting experimenting with fasting mimicking diets.

What Is A Fasting Mimicking Diet (FMD)?

Through years of research, Longo and his team found that the benefits of fasting are produced by the restriction of specific nutrients — protein and glucose — that activate pro-aging pathways (mTOR and PKA for my science nerds out there), and that restricting these nutrients mimics effects of fasting while still providing some nourishment (23).

fasting mimicking diet

In simple terms, your cells are constantly receiving signals from hormones in the body based on nutrient availability. Hormones like insulin (triggered by glucose) and insulin-like growth factor-1 (aka IGF-1, triggered by protein) tell your cells to grow and reproduce (4). The absence of these signals triggers the opposite response — rest and repair.

In mice, cycles of FMD have shown to:

• Reduce cancer incidence (3)
• Prevent bone mineral loss (3)
• Promote neurogenesis (3)
• Stimulate stem cell production (3)
• Protect from chemotoxicity (2)
• Regenerate beta cells in models of Type 1 and Type 2 Diabetes (6)
• Remyelinate neuron sheaths in models of Multiple Sclerosis (7)
• Extend lifespan (3)

These remarkable results set the stage for the creation of an FMD for humans. Longo and his team used what they learned in mice to create the ProLon® Fasting Mimicking Diet™.

While they haven’t tested it in humans with chronic diseases yet (although a clinical trial in cancer patients is underway), they did a large clinical trial last year on healthy adults and were able to lower markers of chronic disease with three cycles (8).

The results showed:

• Lower cholesterol
• Lower blood pressure
• Lower levels of C-reactive protein, a marker of inflammation
• Lower IGF-1 hormone, which is what fuels the mTOR pro-aging pathway
• Reduced visceral fat stores, which are also associated with chronic disease

The reduction in visceral fat (fat stored around organs in the abdominal region) was accomplished without a reduction in lean body mass, which is usually a concern with low-calorie diets.

What is the ProLon® Fasting Mimicking Diet™?

The Fasting Mimicking Diet™ is a low-calorie, low-protein, low-carbohydrate, high-fat, 5-day plant-based meal plan that tricks your body into thinking it is fasting so that it may enter a cellular protection and regeneration mode while still receiving all of the essential nutrients.

While the diet is intended to produce a state of nutritional ketosis, it differs from your typical “Ketogenic Diet” in that it is not just low in carbohydrates but also low in protein (~10% of total calories). As noted above, a reduction in protein is necessary in order to reduce IGF-1 and trigger regenerative cellular effects (5).

The diet comes in a box with all of the food you are to eat for the five day period, including soups, nut bars, tea, kale crackers (which are actually super tasty), olives, algae oil, an “energy drink” (I explain more about that in my video), and micronutrient supplements.

The diet ranges in caloric content from about 1100 calories the first day to 700-800 the next four days.

What’s Next For Fasting/Fasting Mimicking Diet Research?

USC is currently conducting a phase II clinical trial on breast and prostate cancer patients at Norris Cancer Center and LA County Hospital using another FMD called Chemolieve®.  It is specifically formulated for cancer patients and is intended to reduce the adverse effects of chemotherapy and enhance cancer cell death, through a mechanism known as “Differential Stress Resistance” (9).

I had the opportunity to work on the trial during my dietetic internship and the research they’re doing is extremely exciting.

However, ProLon® is not approved by the FDA to treat or prevent any disease and is only currently intended to promote longevity.

FYI, Longo does not benefit financially from sales of Prolon®. He puts all of his earnings in the company back into his research at USC.

So Why Did I Try a Fasting Mimicking Diet?

I tried a Fasting Mimicking Diet

I want to live a long, healthy life!

I want a healthspan to match my lifespan.

My maternal grandmother died at the age of 52 from colon cancer. I was only two at the time, and I never got to know her, but it was very hard on my mother as they were extremely close. My grandmother’s sister also passed away from the colon cancer at an early age, and both of my paternal grandparents died in their 60’s of heart disease.

Cancer and cardiovascular disease run in my family. I don’t need to live to 100, but I do want to live long enough to see my children’s children and to live those years free from chronic disease.

I trust the research. And it shows that the Fasting Mimicking Diet is one of our best ways to promote longevity.

My 5-Day Fasting Mimicking Diet Video Diary

So, you want to see what five days on the diet was like? Check out my FMD video diary – fast forward to 2:39 to skip the intro. >>

Tips for Trying A Fasting Mimicking Diet

If you plan to try ProLon®, here are a few tips to help you through:

fasting mimicking diet from prolon

Do it with a friend. Sticking to the diet can be challenging, but having a support system to provide resolve and encouragement makes it easier. Shout out to my husband for doing it with me!
Stay hydrated. Your body can mistake thirst for hunger. Don’t put yourself at an added disadvantage by becoming dehydrated. Drinking a lot of water and decaffeinated tea throughout the day was very helpful for me.
Buy a bunch of caffeine-free tea or try something like Teeccino if you’re a coffee-fiend like myself. While you are technically allowed one cup of coffee a day while on Prolon, researchers believe to achieve the maximum effect, you should avoid it.
Stay busy. The more your mind is engaged in activities, the less time you’ll be thinking about food. Read a good book, go for a walk, chat with friends, stay out the kitchen!

Longo recommends healthy adults do the diet 1-2 times a year, and those with biomarkers for chronic disease do it up to monthly. I feel so strongly about the benefits of fasting and the promise of the fasting mimicking diet that I will definitely do it again soon.

Want to try ProLon®?

Use my code: ENG10 for 10% off your purchase!

The code is good until 10/31/17.

the fasting mimicking diet l-nutra

*Disclaimer: The information on this website is not intended to serve as medical advice. The statements on this site have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. The Fasting Mimicking Diet may not be right for everyone, certain conditions preclude the use of this diet. Talk to your doctor or dietitian before beginning any new diet.

**I was not paid for my review or promotion of ProLon; however, I do receive a small commission on sales of the product. I thank you for your support of partnerships that support the operation of this blog.


  1. Fontana et al. (2010). Extending the Healthy Lifespan – From Yeast to Humans. Science 16, 321-326.
  2. Cheng et al. (2014). Prolonged Fasting Reduces IGF-1/PKA to Promote Hematopoietic-Stem-Cell-Based Regeneration and Reverse Immunosuppression. Cell Stem Cell 14, 810-823.
  3. Brandhorst et al. (2015). A Periodic Diet That Mimics Fasting Promotes Multi-System Regeneration, Enhanced Cognitive Performance, and Healthspan. Cell Metab. 22, 86-99.
  4. Longo et al. (2015). Fasting: Molecular Mechanisms and Clinical Applications. Cell Metab. 19, 181-192.
  5. Fontana et al. (2008). Long-term Effects of Calorie or Protein Restriction on Serum IGF-1 and IGFBP-3 Concentration in Humans. Aging Cell 7, 681-687.
  6. Cheng et al. (2017). Fasting-Mimicking Diet Promotes Ngn3-Driven β-Cell Regeneration to Reverse Diabetes. Cell 168, 775-788.
  7. Choi et al. (2016). A Diet Mimicking Fasting Promotes Regeneration and Reduces Autoimmunity and Multiple Sclerosis Symptoms. Cell Reports 15, 1-11.
  8. Wei et al. (2017). Fasting-Mimicking Diet and Markers/Risk Factors for Aging, Diabetes, Cancer, and Cardiovascular Disease. Sci. Transl. Med. 9, eaai8700.
  9. Raffaghello et al. (2008). Starvation-dependent differential stress resistance protects normal but not cancer cells against high-dose chemotherapy. PNAS 105, 8215–8220.
  10. Song et al. (2016). Association of animal and plant protein intake with all-cause and cause-specific mortality. JAMA Intern. Med. 176, 1453-1463.

Not ready to try a fasting mimicking diet? Switching to a more plant-based diet is another effective way to reduce biomarkers of chronic disease (10).

Start by trying one of these delicious, vegan recipes! >>

Easy Veggie Burgers

Quick Chickpea Coconut Curry

Vegan Tostadas

Weigh in: Are you interested in learning more about fasting or the research on fasting mimicking diets? There is SO MUCH MORE out there. I can go in depth into specific conditions if you are interested. Let me know in the comments below!


  1. Amanda Howard says:

    Yes – please go more in depth! I could read or talk about health, the body and nutrition all day, everyday! This was the most facinating blog post ever and I love the Healthspan/Lifespan equation to promote longevity. Longo pouring all the money back in is just so wonderful. This is an amazing post! Well done on making it through and that you plan to do it again soon – wow! Great video diary of your 5 day FMD too.

  2. i have always been curious about fasting from a cultural/religious point of view..I am interested to learn more about this and the research in general.

  3. I was following you doing this on Insta and was so interested by it. This is a really great, in-depth explanation that makes sense. I am so interested in trying this!

  4. Interesting! So far I’ve been sticking with wine for anti-aging;)
    Although seeing as I’m someone who will go all day without eating then eat a lot before bed I think I’m an accidental intermittent faster, so would be curious to hear more about fasting…
    Ellen recently posted…The edge: Côte de Brouilly and rose to raspberry to bloody pastillesMy Profile

    • Whitney English says:

      Those polyphenols are great antioxidants! Glad to hear you’re interested in doing more. I will do a post on the difference between intermittent fasting (IF) and periodic fasting (which is what this and water fasting are) sometime soon!

  5. Can you share the approximate cost? It looks like on the website you have to get signed up with a health care provider or have an HCP code, but I’d like to have an idea of how much this investment is so that I can plan accordingly.

    • Whitney English says:

      Of course! It’s $299 but if you buy 3 (so doing it 3 months in a row, which is what the participants in the clinical trial did) it comes down to $250 each. Then you can use my code ENG10 for 10% off that.

  6. Very informative and interesting! Love the way you condensed a lot of information.

  7. Whitney, your post and video diary were fascinating! I’ve never thought I could do a fast but the FMD is a definite possibility!

  8. I’ve been wanting to delve into the research on this. Great info Whitney! And I love your video.
    Lauren O’Connor recently posted…One-Pot Madras Curry Meal {Recipe Redux}My Profile

  9. Thanks for the super informative post! I saw your video on this as well, and really enjoyed it!
    Abbey Sharp recently posted…Is Non Celiac Gluten Sensitivity Real? | Debunking Myths on Gluten IntoleranceMy Profile

  10. Fascinating read!

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