Why do I feel tired after eating? Causes and prevention

Below are some factors that may contribute to feeling tired after eating.

A 2023 review states that certain meal components may directly affect sleep and fatigue.

The authors offer the example of tryptophan, a type of amino acid. When the body metabolizes tryptophan, it helps to produce serotonin, which may induce drowsiness. Serotonin is a chemical that plays a role in regulating mood and sleep cycles.

Dietary sources of tryptophan include the following:

An unhealthful or unbalanced diet may be high in processed foods, such as fast food, which are typically low in nutrients and calorie-rich. This type of diet may not provide a person with adequate amounts of the vitamins, minerals, and antioxidants they need.

A 2018 study suggests people may be likelier to experience fatigue after a large or calorie-rich meal. However, the authors highlight that researchers do not fully understand the mechanisms behind fatigue after eating.

A 2017 study of 13 adult males with no food allergies or requirements examined the effects of eating times on the performance of night shift workers in Australia.

Participants who ate a meal at 1:30 a.m. had lower alertness than those who did not eat all night. However, those who did not eat experienced increased hunger and other gastric complaints.

Both groups of participants reported increased fatigue at 4 a.m., so the study authors suggest that the time of day may have a greater effect on sleepiness than food intake.

However, it is important to note that this is a very small study with a very restricted population sample. These effects may not extend to different populations, including people who do not participate in night shift work.

Further research is necessary to understand how the time of day may affect fatigue after meals.

The following factors may contribute to general fatigue, which a person may notice after eating:

Many people experience a dip in energy after eating. Large meals and meals rich in tryptophan may contribute to sleepiness after meals. The time of day may also contribute to this effect.

Lifestyle changes, such as getting regular exercise, practicing good sleep habits, and limiting caffeine, may help to reduce feelings of fatigue after meals.

However, if these changes do not have any effect, people should speak with a doctor to ensure there is no underlying medical cause.