What is Causing Fatigue After Eating?

By Sabina Rebis, MD
Medically reviewed checkmarkMedically reviewed
April 15, 2022

Are you suffering from recurring bouts of drowsiness after eating?

If it’s more than just the annual Thanksgiving Day turkey dinner crash and you’re experiencing fatigue after you eat on a regular basis, you may have postprandial somnolence.

But what causes tiredness after meals, and how can you combat this common issue?

In this article, I’ll go over what postprandial somnolence is and what may cause your fatigue after eating.

I’ll also discuss how you can prevent it and when to see a doctor.

What is Postprandial Somnolence?

When we break down the term, “postprandial” means after a meal, and “somnolence” means drowsiness or sleepiness.

So, postprandial somnolence is a condition where a person regularly feels drowsy or sleepy after a meal.

If you suffer from postprandial solmonescense, you may find yourself overcome with the urge to lie down for a nap after mealtime.

There are several potential causes for this dilemma, and more than one factor may be involved.

Causes

Typically, there is no  single factor to blame for instances of postprandial solmonescense, but there are some common situations when tiredness sets in immediately after eating.

For some people, this is an event that happens a few times a year in a “perfect storm” of circumstances.

For others, it’s an ongoing issue that can cause serious problems.

Diet

Your diet can directly affect whether or not you feel fatigued after meals.

If you’re eating foods  that you have an allergy or intolerance to (for example, if you have celiac disease) then your body has to use energy to combat the corresponding inflammation and immune response to your diet.

If you have other symptoms besides fatigue after eating, such as stomach upset or skin irritation, you might want to consider allergy testing in order to change your diet and avoid foods that may be causing these symptoms. 

One study related to truck drivers and road drowsiness found correlations between drowsiness and the time of day the truckers ate and what kind of diet they followed.

A “prudent” diet (one high in whole grains, fruits, vegetables, low fat dairy, and legumes) was associated with less drowsiness.

Types of food

The types of foods you’re eating can also affect how hard drowsiness hits you after a meal.

Foods that are high in tryptophans can make you feel slow and sluggish after a meal—that age-old turkey food coma at  play. 

Studies have shown that a diet rich in tryptophan can improve sleep quality and lead to less time spent lying awake in bed.

L-tryptophan in particular helps raise levels of serotonin, the feel good chemical in your brain that makes you feel relaxed and free from anxiety—another good inducer of peaceful rest.

In addition to turkey, other foods, including chicken, fish, tofu, beans, nuts and seeds, egg whites, oats, chocolate, and milk also have high levels of tryptophan.

These foods are also high in protein.

Eating high-protein foods can cause the body to expand more energy and go into overdrive as it tries to digest and break down the fuel.

This excess energy expenditure can lead to fatigue which  may be compounded with the consumption of carbohydrates.

High fat meals can also play a part in postprandial somnolence.

In one study involving both men and women, it was noted the participants who ate meals high in fat and low in carbohydrates felt drowsier in the hours after their meal than those who ate a meal higher in carbs/simple sugar and lower in fat. 

Digestion cycle

How your digestion cycle operates can also affect if you are fatigued after a meal or not. 

The intestine requires a supply of blood to help digest food.

Blood is redirected to help with digestion.

This change in blood flow leads to an increase in heart rate.

Blood vessels in parts of the body not associated with digestive organs constrict, and those in digestive organs dilate or wide. 

In older individuals, these mechanisms may not be as functional as in younger individuals.

As blood is redirected to help with digestion, blood vessels in other parts of the body may not constrict as well.

Blood pressure may then fall and lead to postprandial hypotension, which can lead to fatigue, lightheadedness and other symptoms . 

 One study noted marked changes in blood circulation and flow patterns after lunch that were more marked when the participant had skipped breakfast.

Size of meal

The amount of food that  you eat can  affect how much of your body’s resources are tasked with digestion.

When you eat a larger meal, your body may feel the need to “shut down” while it handles the monumental task of breaking all of that food down.

Time of meals

The time you eat can affect whether or not you experience postprandial fatigue.

Your body has a natural circadian rhythm, with different phases during which your brain and body handle different tasks.

There’s a natural slump in the afternoon, usually between 2 and 5 PM, when your body gathers its resources to give you a burst of energy in the evening.  

This can work against you if you change the time of day you eat a big meal.

If you rarely eat a large breakfast, have lunch on the run, and eat your biggest meal at dinner, your body gets used to processing your most substantial meal of the day in the evening.

If you go to brunch with friends and change this habit, your body might think it’s time for a scheduled digestion break and you may feel more fatigued. 

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Sleeping habits

Your sleeping habits also affect your circadian rhythm, and again, disrupted sleeping patterns can affect digestion.

If your work shift constantly changes and you eat at different times, your cycle can be thrown off.

If you always time your big meal before your scheduled rest time, your body may be primed to rest. 

Physical activity

Casual physical activity directly after eating can help control spikes in blood glucose and reduce the amount of insulin your body needs to release to handle your blood sugar levels.

Light exercise after eating such as walking, also releases endorphins and can boost your mood and energy level, helping you stave off postprandial solmonescence.

But be sure not to go overboard: hard workouts after eating can cause digestive upset and stomach cramps, so stick to a brisk walk instead of a full workout.

Health conditions

If you have certain health conditions, they can also cause a marked reaction to how your body processes meals.

If you are prediabetic or diabetic, or you have insulin resistance, blood sugar levels spiking and corresponding increases in the hormone insulin can may lead to postprandial or reactive hypoglycemia and cause you to feel fatigued.

Other conditions that can contribute to postprandial solmonesence include anemia and celiac disease.  

Prevention Tips

You can help prevent postprandial fatigue by changing a few things about your lifestyle and routine.

Start with a good night’s sleep

If you can get 8 hours of uninterrupted sleep, your body won’t be concerned with paying off a sleep debt, and the likelihood of a post-lunch afternoon energy slump can be decreased. 

Eat small meals

Make it easy on your body by only requiring your digestive system to handle small amounts of food at a time.

Try keeping fruit and nuts around for snacking, and use portion control at mealtime while eating a wide range of simple carbohydrates, complex carbohydrates, proteins, and healthy fats.

This will also help to keep blood glucose levels and insulin levels more stable throughout the day.

Eat frequently

Take added stress off of your body by eating many small meals throughout the day instead of one large meal.

This will help teach your body that it doesn’t have to shut down in order to process a meal.  

Get a nap

If you do need a nap, try to get one before you eat lunch, rather than afterwards.

This will help set you up for success, encouraging your body to use energy gained from the meal to stay active instead of urging rest immediately after eating. 

Keep moving

Some light exercise during the day, like a brisk walk after a meal, can keep your body awake and alert and help reduce the impulse to crash after lunch or dinner.  

Skip the lunch-hour cocktails

Don’t drink alcohol with your mid-day meal, as it can make you feel more tired, adds empty calories, and can spike your blood sugar levels.

Instead, eat lightly if you go for drinks after work, and don’t forget to hydrate.

Step into the light 

Bright light, such as sunlight, can help improve alertness.

Getting outside for a few minutes, or even eating lunch outside, can help reduce your after-meal fatigue levels.

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When to See a Doctor 

If you struggle frequently with fatigue after eating, and changing your routine and lifestyle haven’t helped, it’s time to see a doctor.

This is especially important if you commonly have to drive during that time of day, or operate heavy machinery.

A physician can run tests to see if you are anemic or have a blood sugar problem, and recommend the best course of action. 

How K Health Can Help

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Download K to check your symptoms, explore conditions and treatments, and if needed text with a provider in minutes. K Health’s AI-powered app is HIPAA compliant and based on 20 years of clinical data.

Frequently Asked Questions

What would cause extreme fatigue after eating?
Fatigue after eating can be caused by what you’re eating, how much, or when you eat, or a combination of all three. Other possible causes for after-meal fatigue include conditions like diabetes or anemia, or even celiac disease. Even your sleep patterns and activity levels can affect how you feel after a meal.
How do I avoid fatigue after eating?
Eating frequent, small meals can help you avoid fatigue after eating. Make sure you get enough sleep and maintain a sufficient level of activity. Finding a daily routine that works and sticking to it can help you stave off fatigue after meal times.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Sabina Rebis, MD

Dr. Sabina Rebis is a board certified family medicine physician with over 5 years of primary care and urgent care experience.