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Food Coma: What It Is, and How to Prevent It

Have you ever felt sleepy or sluggish after eating a big meal? If so, you may have experienced what is commonly known as a food coma. But what exactly is a food coma, and why does it happen? Is it harmful, and can you avoid it? In this blog post, we will answer these questions and more, using the latest scientific evidence and some practical tips.

What is a food coma?

A food coma, also known as postprandial somnolence, is the feeling of tiredness or decreased energy levels that can occur shortly after eating a meal. Postprandial means after eating, while somnolence means sleepiness. People with food coma may experience the following symptoms after eating:

  • drowsiness or sleepiness
  • low energy levels
  • lack of focus or concentration

The symptoms may last for a couple of hours or more, depending on the type and size of the meal, and other factors.

What causes a food coma?

There are different theories about what causes food comas, ranging from the types of food that a person eats during a meal to shifts in the circadian rhythm. The circadian rhythm is the body’s internal clock, which regulates sleep patterns. Below, we look at some of the most popular theories about postprandial somnolence and the science behind them.

The type of food

Meals that are rich in carbohydrates can help the body absorb tryptophan, which is an amino acid that the body uses to create serotonin. Serotonin is a hormone that helps regulate sleep, digestion, and mood, which may account for that common post-meal feeling of happiness, sleepiness, and satiety.

Protein-rich foods also contain tryptophan, so eating meals that are rich in protein and carbohydrates may be more likely to induce feelings of sleepiness after eating. A 2021 study of Chinese truck drivers found that those who primarily ate vegetables and staple foods, such as grains, dairy, and eggs, were less likely to exhibit dangerous driving techniques than truck drivers who mostly ate meat and fish, which are high in protein. The researchers suggest that this could be due to the underlying differences in fatigue after eating.

Foods that are high in tryptophan include:

  • lean poultry, such as chicken and turkey
  • fish
  • tofu
  • beans
  • milk
  • nuts and seeds
  • egg whites

Foods that are high in carbohydrates include:

  • refined or highly processed foods, such as white bread, pastries, and sodas
  • starchy foods, such as pasta, potatoes, and rice
  • grains, including oats and quinoa

The size of the meal

Research into the sleep patterns of fruit flies found that sleep was much more likely after a large meal than after a small meal, especially if that meal was high in protein or salt. In a study in men who ate pizza, those who overate reported less energy and more physical tiredness, sleepiness, and lethargy in the 4 hours after eating, while those who ate only until comfortably full had no adverse effects.

Eating a large meal may also affect the levels of glucose and insulin in the blood, which can influence the brain’s activity and alertness. Glucose is the main source of energy for the cells, while insulin is the hormone that helps the cells take up glucose from the blood. After eating, the blood glucose levels rise, and the pancreas releases insulin to lower them. However, if the meal is too large or too high in carbohydrates, the blood glucose levels may spike and then drop rapidly, causing a phenomenon known as reactive hypoglycemia. This can lead to symptoms such as:

  • hunger
  • shakiness
  • weakness
  • dizziness
  • confusion
  • irritability
  • headache
  • sleepiness

The circadian rhythm

The circadian rhythm is the natural cycle of physical, mental, and behavioral changes that the body goes through in a 24-hour period. It affects various aspects of health, such as sleep, mood, metabolism, and hormone production. The circadian rhythm is influenced by external cues, such as light and temperature, as well as internal factors, such as genes and hormones.

One of the hormones that plays a key role in the circadian rhythm is melatonin, which is produced by the pineal gland in the brain. Melatonin helps regulate the sleep-wake cycle, and its levels usually rise in the evening and fall in the morning. However, melatonin production can also be affected by food intake, especially by foods that contain tryptophan. Therefore, eating a meal that is high in tryptophan may increase the levels of melatonin and make the person feel sleepy.

Another factor that may contribute to the circadian rhythm is the post-lunch dip, which is a natural decline in alertness and performance that occurs in the early afternoon, usually between 1 p.m. and 3 p.m. This dip is not necessarily related to food intake, but rather to the interaction between the two main components of the circadian rhythm: the homeostatic sleep drive and the circadian alerting signal.

The homeostatic sleep drive is the pressure to sleep that builds up during the day, while the circadian alerting signal is the signal that keeps the person awake and alert. These two components have opposite effects on the sleep-wake cycle, and they vary throughout the day. The homeostatic sleep drive is low in the morning and high in the evening, while the circadian alerting signal is high in the morning and low in the evening. However, there is also a secondary peak of the circadian alerting signal in the early afternoon, which coincides with a secondary dip of the homeostatic sleep drive. This creates a window of opportunity for a nap, or a food coma, depending on the person’s preference.

How to prevent a food coma

While a food coma may not be harmful in itself, it can affect the person’s productivity, mood, and quality of life. Therefore, some people may want to prevent or reduce the effects of postprandial somnolence. Here are some tips that may help:

  • Eat smaller and more frequent meals, rather than large and infrequent ones. This can help avoid overloading the digestive system and spiking the blood glucose levels.
  • Choose foods that are low in glycemic index (GI), which is a measure of how quickly a food raises the blood glucose levels. Low-GI foods include whole grains, legumes, fruits, vegetables, nuts, and seeds. High-GI foods include refined grains, sugary foods, potatoes, and white rice.
  • Balance the intake of carbohydrates, protein, and fat. Carbohydrates provide energy, protein helps build and repair tissues, and fat supports hormone production and absorption of fat-soluble vitamins. A balanced meal can help prevent nutrient deficiencies and cravings, as well as moderate the blood glucose and insulin response.
  • Drink plenty of water, especially before and during meals. Water can help prevent dehydration, which can cause fatigue and headaches. It can also help fill up the stomach and reduce the appetite.
  • Avoid alcohol and caffeine, especially in the evening. Alcohol and caffeine can interfere with the quality and quantity of sleep, which can affect the energy levels and mood the next day. Alcohol can also impair the liver’s ability to regulate the blood glucose levels, which can worsen the symptoms of reactive hypoglycemia.
  • Exercise regularly, preferably in the morning or afternoon. Exercise can help boost the metabolism, improve the blood circulation, and enhance the mood and cognitive function. It can also help lower the blood glucose and insulin levels, and increase the sensitivity of the cells to insulin. However, avoid exercising right after a meal, as this can divert the blood flow from the digestive system to the muscles, and cause indigestion or nausea.
  • Follow a consistent sleep schedule, and aim for 7–9 hours of sleep per night. Sleep is essential for the health and well-being of the body and mind. It helps restore the energy levels, consolidate the memory, regulate the hormones, and strengthen the immune system. A regular sleep pattern can also help synchronize the circadian rhythm and optimize the sleep quality.
  • Take a short nap, if possible. A nap can help refresh the mind and body, and improve the alertness and performance. However, naps should be limited to 10–20 minutes, and avoided in the late afternoon or evening, as they can interfere with the night-time sleep.


Q: Is a food coma a sign of diabetes?

A: No, a food coma is not a sign of diabetes. Diabetes is a chronic condition that affects the way the body processes glucose, the main source of energy for the cells. People with diabetes have either insufficient or ineffective insulin, the hormone that helps the cells take up glucose from the blood. As a result, they have high blood glucose levels, which can cause various complications, such as nerve damage, kidney damage, eye damage, and cardiovascular disease.

However, some of the symptoms of diabetes may overlap with those of a food coma, such as:

  • increased thirst and urination
  • hunger
  • fatigue
  • blurred vision
  • headaches

Therefore, if a person experiences these symptoms frequently or severely, they should consult a doctor and get tested for diabetes.

Q: Can a food coma cause weight gain?

A: A food coma itself does not cause weight gain, but it may be associated with some factors that can contribute to weight gain, such as:

  • eating large or heavy meals, which can increase the calorie intake, which can exceed the energy expenditure.
  • choosing foods that are high in fat, sugar, or salt, which can stimulate the appetite and cause overeating
  • drinking alcohol, which can add empty calories and impair the judgment and self-control
  • being less physically active, which can reduce the calorie expenditure and muscle mass

Therefore, to prevent weight gain, it is advisable to follow a balanced and moderate diet, limit the alcohol consumption, and engage in regular physical activity.

Q: How can I tell if I have a food allergy or intolerance?

A: A food allergy is an abnormal immune response to a specific food or food component, such as a protein. A food intolerance is a non-immune reaction to a food or food component, such as a carbohydrate. Both food allergy and intolerance can cause unpleasant symptoms after eating, but they are different in their severity, mechanism, and treatment.

Some of the common symptoms of food allergy include:

  • hives, itching, or rash
  • swelling of the lips, tongue, throat, or face
  • difficulty breathing, wheezing, or coughing
  • nausea, vomiting, or diarrhea
  • dizziness, fainting, or low blood pressure
  • anaphylaxis, which is a life-threatening reaction that requires immediate medical attention

Some of the common symptoms of food intolerance include:

  • bloating, gas, or cramps
  • nausea, vomiting, or diarrhea
  • headache, fatigue, or irritability
  • heartburn, acid reflux, or indigestion

The only way to diagnose a food allergy or intolerance is to consult a doctor and undergo some tests, such as a skin prick test, a blood test, or an elimination diet. The treatment for food allergy is to avoid the offending food and carry an epinephrine auto-injector, which can reverse the symptoms of anaphylaxis. The treatment for food intolerance is to limit or avoid the offending food and take medication or supplements that can help digest it, such as lactase for lactose intolerance or antacids for acid reflux.


A food coma is a common phenomenon that can occur after eating a large or heavy meal, especially if it is high in carbohydrates or protein. It is characterized by sleepiness, low energy, and reduced alertness. A food coma is not harmful in itself, but it can affect the person’s productivity, mood, and quality of life. Therefore, some people may want to prevent or reduce the effects of postprandial somnolence. Some of the strategies that may help include eating smaller and more frequent meals, choosing low-GI foods, balancing the intake of macronutrients, drinking plenty of water, avoiding alcohol and caffeine, exercising regularly, following a consistent sleep schedule, and taking a short nap if possible. A food coma is not a sign of diabetes or a cause of weight gain, but it may be associated with some factors that can contribute to these conditions. A food coma is also different from a food allergy or intolerance, which are immune or non-immune reactions to specific foods or food components. These conditions can cause serious symptoms and complications, and require medical diagnosis and treatment.

We hope you enjoyed this blog post and learned something new about food comas. If you have any questions or comments, please feel free to leave them below. Thank you for reading! 

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