I get this question a lot in comments sections of many of my articles: Can intermittent fasting work for vegans?

Although I have no personal experience with vegan diets, I have researched the scientific literature so you won’t have to. The short answer is that vegans can implement an intermittent fasting regimen and benefit from it in the same way as omnivores do. Moreover, there are many side benefits to being vegan:

  • You consume more polyphenols, which promote longevity;
  • It is good for the environment;
  • It is less cruel to animals;
  • It is cheaper.


However, there are a few caveats and nuances. Vegan diets are difficult to manage and require detailed knowledge of nutrition to prevent complications.

Intermittent fasting is more difficult for vegans

The most obvious nuance is that vegan diets are typically high in carbohydrates, which makes nutritional ketosis nearly impossible without a significant reduction in overall calorie intake or prolonging the fasting periods.

If you have been reading the articles on this site, you will understand why higher carbohydrate intake poses a problem for weight management and prevention of metabolic syndrome. Excess inflammation results from higher glycemic loads, which are difficult to avoid as a vegan with our modern food infrastructure. The vegan food on offer in the isles in the supermarket is mostly high in refined carbohydrates, which is not how humans evolved to eat.

Yes, you can build muscle mass on vegan diets

It is of note that many well-known athletes have managed to make vegan diets work. Heavyweight champion David Haye and tennis champion Venus Williams are examples of athletes who are able to maintain performance on vegan diets. But none come nearly close to what this man has managed to achieve:

The video above shows an event in 2013 when Dr. Nun Amen Ra set a world record in deadlifting. What is more impressive than his clearly superior performance is that he achieved this feat by practicing a strict intermittent fasting regimen of 1 vegan meal per day.

His site describes a daily fasting period 23 hours in duration, wherein no calorie-containing food is consumed. He consumes one meal at night after a high-intensity exercise, but the meal is completely devoid of animal-based proteins. He manages to get the full spectrum of amino acids by consuming rice, legumes, seeds, nuts, and amino acid supplements within the 1-hour feeding window.

Managing Deficiencies in Vegan Diets

Vegan diets are typically low in protein. They are specifically low on Branched Chain Amino Acids (BCAA). Amino acids such as lysine, methionine, threonine, and tryptophan are most commonly absent in vegan diets. Vegans also have lower levels of muscle creatine and carnosine. These protein deficiencies can be alleviated by supplementing with BCAA, creatine, and β-alanine. Increasing intake of legumes, chickpeas, lentils, soy beans, nuts, and seeds ensures the availability of an adequate variety of amino acids.

Vitamin B12 (cobalamin) is also in short supply with vegan food. Vitamin B12 is essential for a healthy nervous system, homocysteine metabolism, and DNA synthesis. Vitamin B12 deficiency is why many vegans develop megaloblastic anemia and neuropathy.

Unfortunately, B12 supplements are not very effective because the body has a limited capacity to absorb them orally. Sublingual drops, lozenges, and transdermal products that are marketed to offer better absorption, but there is a lack of research supporting such claims. Vegans need to monitor B12 levels with the help of their medical providers. Subcutaneous or intramuscular injections might be the only solution in some cases of severe deficiency.

Vitamin D deficiency is also problematic for maintenance of bone density, which is essential for longevity. Vitamin D is especially important for children and teenagers. Short but frequent exposure to the sun in the early and late hours of the day is needed for the body to synthesize its own vitamin D. Otherwise supplementation is essential.

Minerals such as iron, zinc, calcium, and iodine are also less available in the vegan diet. Iron deficiency anemia decreases red blood cell count, which causes fatigue and decreased availability of oxygen for cellular metabolism. Zinc plays an essential role in DNA repair and protein metabolism, which is essential for the purposes of maximizing longevity. Calcium deficiency impairs growth in children and teenagers on a vegan diet. Iodine plays an important role in thyroid function, and it is needed for physical and mental development. Supplementation is very effective at managing deficiencies in these minerals.

Low fat intake is a problem

Vegan diets have been proposed as a solution for diabetes and cardiovascular disease, but these benefits are increasingly disputed in the academic literature. Recent research into dietary fat has increased our understanding beyond the highly simplistic saturated vs unsaturated tradeoff.

In hyperlipidemic subjects, one study demonstrates that a vegan diet high in fat and low in carbohydrates promotes better cardiovascular health (lower LDL-C and higher HDL-C) vs. a vegan diet low in fat and high in carbohydrates.

Monounsaturated fatty acids, common in the Mediterranean diet, reduces inflammation, cardiovascular risk, and blood levels of triglycerides. Ketogenic diets and intermittent fasting reduce metabolic syndrome and promote longevity by increasing dietary fat and minimizing carbohydrates.

The insufficient availability of fats, especially long-chain omega 3 fatty acids EPA and DHA, poses some challenges for vegans. Consumption of healthy fats (olive oil, avocados, nuts, and seeds) is essential for rebuilding cells and reduction of inflammation. Dietary omega 3 supplements may be necessary because there are very few plant-based sources that are bioavailable. While flax seeds, walnuts, and chia seeds do contain omega 3 fatty acids, they are not as easily absorbed as omega 3 from seafood. Vegans must also be more vigilant to reduce the pro-inflammatory omega 6 fatty acids from sources like sunflower seeds and corn.

Increasing fat intake is also necessary to maintain testosterone levels in males, which are lower under a vegan diet. This is especially of interest to athletes who are in need of maximizing the anabolic metabolism necessary for building muscle mass.

Concluding Remarks

I wrote this article to help vegans understand that intermittent fasting and plant-based diets are not mutually exclusive. Nutritional ketosis is also possible under a plant-based diet, and many people have succeeded at implementing it. I often go several days consuming plant-based food and continue to be in nutritional ketosis. Although I am not at a period in my life to try out a completely vegan diet, I do consider it an option in the future.


Jenkins, David J. A. et al. “The Effect of a Plant-Based Low-Carbohydrate (“Eco-Atkins”) Diet on Body Weight and Blood Lipid Concentrations in Hyperlipidemic Subjects.” Archives of Internal Medicine 169.11 (2009): 1046-1054.

Lowery, Lonnie M. “Dietary Fat and Sports Nutrition: A Primer.” Journal of Sports Science & Medicine 3.3 (2004): 106–117.

Rizzo, Gianluca et al. “Vitamin B12 among Vegetarians: Status, Assessment and Supplementation.” Nutrients 8.12 (2016): 767. PMC. Web. 3 Mar. 2018.

Rogerson, David. “Vegan Diets: Practical Advice for Athletes and Exercisers.” Journal of the International Society of Sports Nutrition 14 (2017): 36. PMC. Web. 3 Mar. 2018.