Tired After Eating? 9 Potential Causes + What To Do About It

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It’s happened to almost all of us at one time or another: you finish a big dinner and find yourself nodding off while trying to relax with your favorite show, or you feel unduly sleepy after lunch at work and would like nothing more than to rest your head on your desk for a quick nap.

However, while feeling tired after eating isn’t particularly uncommon or necessarily a cause for concern, if you’re frequently getting sleepy after you eat, it might be an indication that something else is going on.

In this guide, we will look at the reasons why people can get tired after eating and what to do to prevent feeling sleepy after eating a meal.

We will cover: 

  • Why Do I Get Sleepy After I Eat? Here Are 9 Potential Causes
  • What To Do About Feeling Tired After Eating

Let’s dig in!

A person at her computer yawning, feeling tired after eating.

Why Do I Get Sleepy After I Eat? Here Are 9 Potential Causes

There are several factors that can contribute to feeling tired after eating, some of which are perfectly normal, and others may be a signal that you need to modify your diet or see your healthcare provider. 

Here are the most common causes of feeling tired or fatigue after eating:

#1: Eating Foods High In Tryptophan 

We usually associate tryptophan with the postprandial sleepiness that ensues after your Thanksgiving meal or another big turkey dinner, and it’s true—eating foods high in tryptophan can leave you feeling sleepy.

Tryptophan, an essential amino acid, is used by the body to synthesize various proteins, as well as niacin (a B vitamin) and a molecule known as  5-hydroxytryptophan or 5-HTP. 

Because 5-HTP is a precursor for the neurotransmitter serotonin, and serotonin helps regulate sleep, it’s normal to feel tired after eating foods high in tryptophan

A thanksgiving meal.

Although turkey is the poster child for foods rich in tryptophan, other foods high in tryptophan include the following:

  • Chicken, duck, salmon, oysters, lobster, pork chops
  • Milk, cottage cheese, and other dairy products
  • Tofu, edamame
  • Sweet potatoes, squash, and pumpkin seeds
  • Spinach 
  • Peanut butter
  • Oatmeal

Keep in mind that tryptophan is an essential amino acid, which means you need to consume it because your body cannot manufacture it, so don’t avoid foods with tryptophan altogether.

It’s often helpful to know why you’re feeling tired after eating, so if you are mostly feeling sleepy after eating the foods listed above, innocuous tryptophan may be to blame.

#2: Eating Foods High In Melatonin

Red cherries.

You might have heard of people taking melatonin supplements to support their sleep, or perhaps you’ve tried them yourself. Melatonin is a hormone produced naturally in the pineal gland in the brain. 

Among several functions, melatonin plays a key role in regulating the body’s circadian rhythms or sleep-wake cycles. 

While melatonin supplements are a popular way to increase the concentration of melatonin and possibly improve the quality and quantity of sleep, melatonin is also found naturally in some foods. 

Eating foods high in melatonin can increase the levels of this hormone in your body and can leave you feeling tired or fatigue after eating.

Examples of foods high in melatonin include milk, tart cherries, pistachios, grapes, mushrooms, corn, oats, eggs, rice, and bananas.

#3: Drinking Alcohol With Your Meal

Alcohol can cause drowsiness because it’s a nervous system depressant.

Therefore, if you’re enjoying a beer with a late lunch on the weekend, sipping wine or a cocktail with dinner or shortly beforehand, or enjoying a nightcap when your plate is cleared, there’s a good chance the alcohol is having an effect on your body and leaving you feeling tired after eating.

Two glasses of white wine.

#4: Eating Meals High In Carbohydrates 

As with tryptophan in protein-rich foods, foods high in carbohydrates have been shown to increase the production of serotonin. 

Simple carbohydrates also cause your blood sugar (glucose) levels to rise quickly. As a result, the pancreas secretes insulin, a hormone that signals the muscles and liver to take up the circulating glucose. 

Blood sugar levels can then dip, leaving you feeling tired. This hypoglycemia and low energy after eating foods high in simple carbohydrates are particularly common in people with type 2 diabetes, pre-diabetes, and insulin resistance.

There is also evidence to suggest that consuming carbohydrates alongside tryptophan increases the absorption of tryptophan. Therefore, some experts think meals high in carbohydrates and protein together will leave you feeling tired after eating.

Foods high in carbohydrates include the following:

  • Bread, bagels, English muffins, pastries, muffins
  • Pasta, rice, legumes
  • Crackers, cookies, candy
  • Fruit
  • Tubers 
  • Cereals, oatmeal, whole grains 
  • Corn
  • Juice
An arrangement of foods such as apples, potatoes, legumes, vegetables and nuts.

#5: Eating a Big Meal

When it comes to feeling tired after eating, it’s not just what you eat but also how much you eat. Large, rich, heavy meals, especially if they are high in fat, take longer to digest.

Digestion is metabolically demanding, so it takes energy to start breaking down a large meal once it hits the stomach. This can leave you feeling sluggish after eating.

#6: Inadequate Sleep

Although poor sleep or chronic sleep deprivation can leave you feeling tired at any point of the day, people who are overtired and need more sleep often feel particularly sleepy after eating because when the body is relaxed and full, it’s even easier to nod off.

#6: Food Intolerances and Food Allergies

If you’re eating something that doesn’t agree with you, you might feel tired after eating. One of the signs of a food intolerance or food allergy can be sleepiness after eating.

When you have a food intolerance or food allergy, the body produces histamines after eating the offending food. Histamines can increase the feeling of drowsiness, leaving you feeling fatigued.

A chalkboard that says celiac disease and a stethoscope on it.

#7: Celiac Disease 

If you are feeling tired after eating, particularly if you are sleepy after eating wheat, rye, and barley, you may have undiagnosed celiac disease.

Celiac disease is an autoimmune disease that involves an allergy to gluten, a protein found in wheat, rye, and barley, among many other processed foods.

Other signs of celiac disease include bloating, diarrhea, weight loss, and gas. If you are concerned about a gluten intolerance or celiac disease, discuss testing with your healthcare provider or remove all gluten from your diet.

#8: Diabetes

As mentioned, reactive hypoglycemia after eating foods high in simple carbohydrates is a hallmark sign of insulin resistance, prediabetes, type 1 diabetes, or type 2 diabetes. 

Other early signs of diabetes include increased hunger, thirst, and urination.

If you are noticing a pattern of feeling tired after eating carbohydrates, you should consult your doctor about getting your fasting blood sugar and hemoglobin A1c levels checked.

A woman sleeping in bed.

What To Do About it Feeling Tired After Eating 

Here are a few tips to prevent feeling tired after eating:

  • Eat smaller meals more frequently throughout the day.
  • Limit simple sugars.
  • Avoid drinking alcohol, particularly during the day. 
  • Get your ferritin levels checked; anemia can cause fatigue.
  • Get enough sleep.
  • Take a walk or move your body after eating, as exercise can be invigorating.
  • Be mindful of eating meals high in tryptophan and/or melatonin in the morning or middle of the day.
  • Drink more water to stay properly hydrated
  • Keep a food diary to keep track of what you eat and what symptoms you feel to help you identify potential food allergies.

If you have looked at your diet and sleep but are still feeling tired after eating, it’s a good idea to visit your doctor for further testing.

If you are looking to better your nutrition, you can look into the following diets: The Best Popular Diets For Runners

A food diary with an apple next to it.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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