Intermittent fasting is a trendy diet strategy that has been around for ages, literally. Researchers believe that the human genome evolved from 600,000 BC to 25,000 BC. During this time, humans were hunter-gathers who experienced significant energy oscillations; sometimes, there was plenty of food, but other times there was not. This constant flux in energy availability shaped the human genome's development to regulate metabolism for efficient energy use and increased fat storage. Today, while the human genome remains mostly unaltered, our environment has changed drastically. Most of us no longer face food shortages; instead, we lead sedentary lives and eat at least three meals per day.

However, there is little to no scientific evidence that supports the notion that eating at least three meals per day is optimal for health. Indeed, eating at regular intervals every day is arguably mal-aligned with our genome's design. Simultaneously, the health consequences for overfeeding are dire since overfeeding seriously affects human morbidity and mortality. The United States is facing an unprecedented obesity crisis. Therefore, bodyweight reduction is a valuable tool to improve health, enhance the quality of life, and reduce adverse and burdensome public health outcomes.

Caloric restriction is one of the most efficient ways to lose weight, but caloric restriction may also improve normal-weight people's health. Caloric restriction through intermittent fasting, which is fasting and eating only for designated periods, may mimic the ancestral eating patterns for which our genome was designed. In fact, many find fasting easier to adhere to than general calorie restriction. The relatively simple parameters of intermittent fasting do not require adherence to a specific diet, only to nutrient timing alternating "feed" days or times with "fast" days or times.

There are three popular intermittent fasting models:

  1. Alternate day fasting in which eating is unrestricted every other day.
  2. 5:2 intermittent fasting in which eating is unrestricted five days per week and restricted to 500 calories per day two days per week.
  3. Daily time-restricted feeding in which eating is unrestricted during certain hours.

More research is required to determine if one fasting model is more beneficial than another. However, it is worth considering that one of the ideas behind intermittent fasting is that spending more time fasting is better since ketosis is achieved in the fasting state. Nonetheless, intermittent fasting is a more viable dieting option for some people than caloric restriction, and ketosis may be easier to achieve through intermittent fasting.

One incredible benefit of intermittent fasting is how our cells respond to periods without food. Researchers believe cells respond to intermittent fasting by engaging in a coordinated adaptive stress response that promotes DNA repair, down-regulation of inflammation, protein quality control, mitochondrial biogenesis and autophagy, and increased antioxidant defense expression. This cellular pathway, also known as ketosis, is mostly untapped in people who overeat or are sedentary. Other benefits of intermittent fasting disassociated with weight loss include improved glucose regulation, increased abdominal fat loss, and improved blood pressure and heart rate efficacy during endurance training.

While the effects of fasting on athletic performance is a field that requires more study, some research suggests intermittent fasting does not cause muscle loss or decrease muscle force generation. Research shows that intermittent fasting promotes longevity and increase the life span of humans. Brain health and cognitive ability may improve through intermittent fasting. The benefits of intermittent fasting are plentiful for many populations, but you should always consult with your doctor before beginning intermittent fasting.

References:

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  5. de Azevedo, F. R., Ikeoka, D., & Caramelli, B. (2013). Effects of intermittent fasting on metabolism in men. Revista Da Associação Médica Brasileira (English Edition), 59(2), 167–173. https://doi.org/10.1016/s2255-4823(13)70451-x De Cabo, R., & Mattson, M. P. (2019). Effects of intermittent fasting on health, aging, and disease. New England Journal of Medicine, 381(26), 2541–2551. https://doi.org/10.1056/NEJMra1905136