Fasting in athletes and sport

Fasting in sport is a nutritional tool used by many elite athletes for its effectiveness in gaining muscle, losing fat and improving athletic performance. It is only periods or cycles of fasting and eating, interspersed, which improves your health and prevents diseases.

It should be noted that intermittent fasting is not a diet. It is a protocol of distribution of intakes where there are interruptions and continuations of feeding periods at regular intervals.

Fasting has been present since the beginning of our evolutionary history and there are different varieties. Fasting allows the distribution of the total daily caloric intake in certain hours to facilitate a period of fasting in which processes such as autophagy, detoxification, metabolic flexibility, immunological, intestinal, hormonal or neurocognitive improvements are developed.

The most common types of fasting 

Category 1: Total restriction of daily intake on certain days.

Within this category we can find two protocols: 1:1, where we fast every other day, successively, or 2:1, with which, after two days of normal eating, a day of fasting is done, repeating this cycle continuously.

Category 2: Restriction of eating time per day.

Days with periods of fasting alternate with days of normal distribution of intakes. Within the fasting days, the most popular protocols in this category are 16:8, where the window of intakes comprises 8 hours versus 16 hours of fasting, and 20:4, where the time of intakes is reduced to 4 hours.

Benefits of fasting in athletes

Gastrointestinal improvements

Since during the fasting hours the person does not ingest food, the gastric work of the intestine (small and large), the gall bladder or the liver decreases. This time without food intake favors the relaxation of the intestinal system and the regeneration of various processes that may be unbalanced in the day to day intestinal flora, in the release of pancreatic enzymes and bile salts, liver function or processes such as fermentation or intestinal permeability etc..

Increased Catecholamine Production

Increased secretion of epinephrine and norepinephrine increases lipolysis, releasing fatty acids into the bloodstream to be oxidized and used as an energy source. Contributes to decreased glucose utilization which may help muscle glycogen sparing.


When a person performs intermittent fasting, it promotes an improvement in the neurohormonal biorhythms of the organism and benefits can be seen in terms of the release of various hormones. We found a better response in insulin sensitivity, sex hormones (testosterone, estrogens and progesterone) and in the adrenal capsule.

At the neurocognitive level

Nootropic molecules are released (adrenaline, noradrenaline, dopamine, growth hormone, T4 and T3 hormone, brain neurotrophic factor, etc.), which help neurons to function properly.

This makes that one of the first benefits we find is the improvement in brain function, memory, retention of concepts and even a more optimal emotional state.

Improves metabolic flexibility

It is based on the improvement of insulin sensitivity, which facilitates metabolic acceleration and improvement in the oxidation processes of both glucose and fatty acids.