8 Reasons Why You Feel So Tired After Eating (and What to Do About It)

Feeling fatigued after a meal — medically known as postprandial somnolence — is not an uncommon reaction for most. In fact, after big holiday meals like Thanksgiving dinner, you may even expect to feel sleepy and need rest.

But, should eating routinely make you feel extreme fatigue? Likely not.

Extreme fatigue after a meal, accompanied with other digestive issues, could indicate an underlying health condition. The type of food you eat and portion size can also contribute to feelings of fatigue.

Here, Ashkan Farhadi, MD, a gastroenterologist at MemorialCare Orange Coast Medical Center in California, shares the most common factors that can cause you to feel extreme fatigue after eating.

"When you digest food, your digestive tract is getting an increase of blood supply," Dr. Farhadi says. This can reduce blood supply to the brain, causing feelings of sleepiness.

Dr. Farhadi says this feeling is normal, and actually can bring upon a state of calm rather than just fatigue.

"A release of serotonin occurs when you digest food, and the gut is one of the major producers of that serotonin," Dr. Farhadi says. This creates a relaxing effect in the body, causing you to feel calm after eating.

Eating a lot can make you drowsy, especially if you are eating foods higher in protein and carbohydrates (i.e., Thanksgiving dinner, with its turkey centerpiece and array of high-carb foods from stuffing to potatoes).

Everyday foods that are high in protein include dairy, chicken and soy products, while high-carb items include pasta, white bread and sugar, per the Cleveland Clinic. When you eat a lot of these types of foods, your digestive system gets overloaded and your body releases hormones that create sleepiness, according to the Cleveland Clinic.

Additionally, if you are eating highly processed foods or foods with little nutritional value, you may have less energy, according to the National Institute on Aging.

Overwhelming tiredness after eating can be a sign of an underlying medical condition, like diabetes.

Diabetes is a health condition that affects your body's production or use of insulin, which moves glucose (aka sugar) from the foods you eat into your body's cells, per the American Diabetes Association (ADA). For people with diabetes, glucose lingers in the bloodstream, where it can cause an array of problems.

Extreme fatigue is one common symptom of type 2 diabetes, as well as frequent urination, thirst and losing weight without trying, according to the ADA. While "chronic fatigue and diabetes are two separate conditions, hyperglycemia [high blood sugar] can get to the point that it affects the brain," Dr. Farhadi says.

Celiac disease is an immune reaction to eating foods that have gluten. If you have celiac disease, eating gluten will damage your small intestine lining and prevent it from absorbing essential nutrients over time, per the Mayo Clinic. Celiac disease can cause an array of GI symptoms, including bloating, constipation and diarrhea.

Fatigue is also a common symptom for people with celiac disease that have eaten foods with gluten, according to the National Celiac Association.

SIBO — a condition that happens when you have too much bacteria in the small intestine — can cause fatigue after eating. SIBO happens when food passes too slowly through the digestive tract, causing a build-up of bad bacteria, according to the Mayo Clinic.

Other symptoms include, per the Mayo Clinic:

• Diarrhea
• Unintentional weight loss
• Loss of appetite
• Abdominal pain
• Bloating
• An uncomfortable feeling of fullness after eating

SIBO can be diagnosed through a breath test at the doctor's office and is treated with antibiotics.

The quantity of food you eat is another major factor in how you feel after a meal — whether it's nutritious or not.

Eating large quantities of nutritious food (like beans and brown rice, for example) can make you feel tired. Likewise, large amounts of highly processed foods (like chips, pastries or fried foods) can also make you feel like taking a nap afterwards.

When you eat something you're allergic to, your immune system begins working to try and protect your body. This is typically when fatigue sets in.

"Keep in mind that most food allergies come with a variety of other symptoms," Dr. Farhadi says. If you have fatigue alone, it may be another issue. Common food allergens include, per the FDA:

• Milk
• Eggs
• Fish/shellfish
• Peanuts/tree nuts
• Wheat
• Soy

Sometimes the reason you feel fatigued after eating a meal is simple: You're just tired in general.

The body expends energy when eating and digesting a meal, and if you're already sleep-deprived, you can end up feeling even more tired. "The act of eating can be tiresome for people with chronic fatigue syndrome or another illness," Dr. Farhadi says.

Just remember, in most instances, feeling tired after eating a meal is normal and expected, Dr. Farhadi says.

If you overeat, you may feel sleepy, but too full to get the rest your body needs. Dr. Farhadi shares a few tips for sleeping after eating a meal:

• Do not lay flat for three hours after eating a meal. For heavy meals, like Thanksgiving, this could be seven hours, Dr. Farhadi says.
• If you have to sleep, use a couple of pillows to elevate your head to avoid acid reflux. Or, opt to snooze in a semi-seated position, such as on a couch or sitting in a recliner.
• Always lay on your right side with a full stomach. The exit of the stomach is on your right side, so this expedites the exit process, Dr. Farhadi says.
• If you feel digestive upset, take an antacid.