Some Things we Learned From our Five-Day Fasting Mimicking Diet

Fasting and the Fasting Mimicking Diet

Fasting is an ancient practice that is now enjoying a resurgence, due in part to growing scientific evidence on the positive health impacts of both intermittent and prolonged fasting (defined here as a fast of 48 hours or longer). I wrote about the benefits of the various forms of fasting in a previous blog – Fasting: Some Things You Should Know. In this post, I focus on prolonged fasting and in particular the Fasting Mimicking Diet® (FMD), based on the work done by Professor Valter Longo and associates.
Longo, one of the world’s foremost experts in the science of aging, has found that prolonged fasting can significantly increase health and longevity. The benefits of periodic prolonged fasting led Longo to advocate regular five day fasts to enhance cellular health and minimise biological aging for those in good health below the age of seventy. Longo and his team also found that fasting can be an effective treatment for cancer used alongside standard medical practices. Fasting can enhance the effectiveness of chemotherapy for some cancers as it preferentially protects healthy cells and increases the mortality of cancerous cells. Human clinical trials on cancer patients are ongoing but in the meantime some people have adopted fasting while on chemotherapy with some success.

While acknowledging the benefits of fasting, many health care practitioners and patients have been reluctant to undertake a classic non-caloric fast (NCF) for a variety of reasons. This motivated Longo to develop the “fasting mimicking diet.” This consists of a low calorie, low protein and high micronutrient combination, which reproduces biochemical effects of fasting while minimising the risk of nutrient depletion. “ProLon”, a precise combination of foods and supplements, has been commercialised as a package by L-Nutra, of which Longo is the founder. Longo does not personally profit from the venture, thus helping to ensure that his scientific integrity is not compromised.

At $249 per box, ProLon is quite pricey and, of necessity, the food on offer is processed. In an effort to provide the benefits of an FMD using whole foods Chris from Gen X Life is Good!, has developed a DIY version of ProLon, approximating its nutrient mix from Longo’s patents and publications. Many thanks to Chris for all her hard work and her very useful accounts of her experiences on her website.
Julie and I are big fans of a twice-yearly five-day non-caloric fast (drinking mostly water, a little herbal tea and the odd black coffee) but decided to give the DIY FMD a go as our second fast of 2019. We pretty much followed Chris’s meal plans as laid out on her website but incorporated her snacks (potatoes mostly) into either lunch or dinner.

Please bear in mind Valter Longo's caution: He does not recommend doing a “DIY” version of the FMD because it may be ineffective and potentially harmful. If you plan on doing a fast, do your own research and check with your healthcare provider.

It is also important to note that what we are documenting here is anecdotal. It does not represent an objectively designed experiment with randomisation, replication, a control (non-treatment) group for comparison, and measures of health indicators before, during and after the fast.

Fasting Mimicking Diet vs a Non-Caloric Fast

With the above caveats in mind, here is a summary of our experiences of the DIY FMD and a comparison with the non-caloric fast (NCF) we undertook in July 2019.

Hassle:
NCF: No food = no hassle. We found lots of spare time to do other things and to free ourselves from the “tyranny” of food preparation, mealtimes, and washing, drying and putting away.

DIY FMD: We still had to do all the food-related stuff, while catering for those in the family who were eating normally, so the hassle was doubled. The hassle would have been less had we been using ProLon as all the portions are already packaged, but the DIY version meant precise weighing and combining of all ingredients. The recipes were simple so the cooking itself was uncomplicated, but it might be a bit of a challenge for those with less cooking experience than Julie (who made most of the meals) and me (who chipped in on occasion).

Verdict: NCF was the least hassle for us.

Hassle

NCF: No food = no hassle. We found lots of spare time to do other things and to free ourselves from the “tyranny” of food preparation, mealtimes, and washing, drying and putting away.

DIY FMD: We still had to do all the food-related stuff, while catering for those in the family who were eating normally, so the hassle was doubled. The hassle would have been less had we been using ProLon as all the portions are already packaged, but the DIY version meant precise weighing and combining of all ingredients. The recipes were simple so the cooking itself was uncomplicated, but it might be a bit of a challenge for those with less cooking experience than Julie (who made most of the meals) and me (who chipped in on occasion).

Verdict: NCF was the least hassle for us.

Side Effects Including Hunger

NCF: We experienced some headaches on Days 1 and 2 and some dizziness at various times, notably upon standing. This was reflected in our low blood pressure readings (my minimum morning blood pressure was 100/66 and it is normally about 110/70). We both felt very hungry on Day 2.

DIY FMD: We also experienced some headaches on days 1 and 2 but no dizziness despite the fact that my blood pressure readings were lower than normal (minimum morning blood pressure of 102/65). We did not feel very hungry throughout. Although low in calories the food was, in many instances, high in volume and there were times when we found it difficult to finish what was on offer.

Verdict: DIY FMD had the fewest side effects.

​Energy Levels

​Our energy levels dipped on Day 2 of the NCF but were very high from day 3 onwards. The increased energy was accompanied by strong feelings of wellbeing. We experienced neither the highs nor the lows with the DIY FMD.
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Verdict: A tie.

Ketosis

Julie entered ketosis on Day 2 of the NCF and Day 3 of the DIY FMD. It was the reverse for me: ketosis on Day 3 of the NCF and Day 2 of the DIY FMD. 
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Verdict: A tie.

Post-fasting metrics

In both cases, the lost weight was regained after a week. We felt no ill-effects following either fast. Nor did we feel any sustained increase in positive energy, but we are both in good health anyway so it is unlikely that we would feel much change even if there are some subtle underlying shifts. To learn more, we would have needed to test for a variety of biomarkers such glucose, CRP (a marker of inflammation and risk factor for cardiovascular disease), and triglycerides, which is something we may do in the future. In both the NCF and the DIY FMD, our normal diet tasted amazing when we resumed eating, but this effect was greatest following the NCF. 

Verdict: No verdict as we did not have the necessary data.

​Overall verdict

​In answer to the question, “which is the best?” I’ll give the classic evaluator’s response, “It depends…” On balance, Julie and I prefer the non-caloric fast because of its convenience and the fantastic energy from days 3-5. It eliminates any residual nagging doubts about the authenticity of the DIY FMD. However, the DIY FMD might be a better option for those who fear fasting, and those with pre-existing conditions including nutrient deficiencies. 

​References

• Brandhorst S, Choi IY, Wei M, et al. A periodic diet that mimics fasting promotes multi-system regeneration, enhanced cognitive performance and healthspan. Cell Metab. 2015 Jul 7;22(1):86–99.
• Choi IY, Lee C, Longo VD. Nutrition and fasting mimicking diets in the prevention and treatment of autoimmune diseases and immunosenescence. Mol Cell Endocrinol. 2017 Nov 5;455:4–12.
• Choi IY, Piccio L, Childress P, et al. A Diet Mimicking Fasting Promotes Regeneration and Reduces Autoimmunity and Multiple Sclerosis Symptoms. Cell Rep. 2016 07;15(10):2136–2146. 
• Dorff TB, Groshen S, Garcia A, et al. Safety and feasibility of fasting in combination with platinum-based chemotherapy. BMC Cancer. 2016 10;16:360.
• Fontana L, Partridge L, Longo VD. Extending healthy life span: from yeast to humans. Science. 2010 Apr 16;328(5976):321–326.
• Longo VD. The Longevity Diet: Slow Aging, Fight Disease, Optimize Weight. S.l.: Avery Pub Group; 2019.
• Longo VD, Mattson MP. Fasting: molecular mechanisms and clinical applications. Cell Metab. 2014 Feb 4;19(2):181–192. 
• Wei M, Brandhorst S, Shelehchi M, Mirzaei H, et al. Fasting-mimicking diet and markers/risk factors for aging, diabetes, cancer, and cardiovascular disease. Sci Transl Med. 2017 15;9(377).