Why Do I Get Tired After Eating? An RD’s Causes and Solutions

Whether you experience them regularly or every so often, “food comas” (or mini, fleeting versions of them) are a very common and typically entirely harmless phenomenon. And for the most part, so are the causes of them. But what are the precise reasons why you get tired after eating? Ahead, with the help of Kimberley Rose-Francis, RDN, CDCES, CNSC, LD, we’re unpacking three of the most likely contributors.

Why do I feel so tired after eating? An RD’s three key causes:

1. The timing of your meals could be contributing—it’s completely expected

Get tired after lunch? Perhaps your workload isn’t so stimulating, but it’s more likely that your circadian rhythm (aka sleep-wake cycles) is behind your post-lunch, midday slump. “Feeling sleepy after a meal, or postprandial fatigue, can be attributed to several factors, including the circadian rhythm,” says Rose-Francis.

A 2019 review in the Yale Journal of Biology and Medicine notes that our circadian rhythm dips around 2 to 4 p.m. before picking back up in the early evening. In this case, it’s totally normal to feel a bit snoozy after lunch—but the cause is linked more to your innate biological rhythms and when you eat lunch than the meal itself.

“Feeling sleepy after a meal, or postprandial fatigue, can be attributed to several factors, including the circadian rhythm.”
—Kimberley Rose-Francis, RDN, CDCES, CNSC, LD

2. You’re eating foods that encourage sleepiness

If you try to hack your sleep through diet and lifestyle, you’re probably aware that certain foods and drinks can work in your favor to promote ZZZ’s. While this can be immensely helpful when it’s time to hit the hay, sometimes these foods can lead you to feel sleepy during the day, as well. Some of these foods include:

• Tryptophan-rich foods, including lentils, salmon, spinach, peanut butter, pumpkin seeds, cheese, and turkey (hence the infamous Thanksgiving food coma)
• Melatonin-rich foods including pistachios, eggs, and salmon
• Tart cherry juice, which packs both melatonin and tryptophan
• Milk, which also packs melatonin and tryptophan
• Chamomile tea

“Vitamin D-rich foods like fatty fish, egg yolks, mushrooms, and fortified foods may directly and indirectly regulate sleep,” Rose-Francis adds.

“Vitamin D-rich foods like fatty fish, egg yolks, mushrooms, and fortified foods may directly and indirectly regulate sleep,” Rose-Francis adds.

3. You’re eating more high-fat foods than usual—which may mean more or less balance in your diet

An older study published in the journal Physiology & Behavior investigated the effects of a high-fat, low-carb breakfast and a low-fat, high-carb breakfast in 18 men and women. Participants who ate the high-fat, low-carb breakfast reported feeling more sleepy two to three hours after eating, and significantly more fatigued after the three hour mark compared to the other group.

The researchers discovered that concentrations of cholecystokinin, a hormone in the GI system that stimulates the digestion of fat and protein, were significantly higher after the high-fat, low-carb meals. Cholecystokinin is linked to both satiety and sleepiness—with fatty acids and amino acids in particular triggering its release—so a meal rich in these components might lead you to feel snoozier than usual.

It’s important to remember that healthy fats and protein are crucial to include in a well-balanced diet, and failing to get in your macros and micros alike can take their toll on your energy levels and overall health. Read: Don’t skimp on them for the sake of mitigating post-meal fatigue.

It’s important to remember that healthy fats and protein are crucial to include in a well-balanced diet, and failing to get in your macros and micros alike can take their toll on your energy levels and overall health. Read: Don’t skimp on them for the sake of mitigating post-meal fatigue.

The bottom line

Just as certain foods can fuel your body with more energy, some might end up leaving you feeling more tired than usual. There’s a chance some of your go-tos to promote ZZZ’s at nighttime may work earlier than you’d like—but, all things considered, Rose-Francis says more robust research is needed to understand how different foods impact the sleep-wake cycle.

In addition, again, minor post-lunch fatigue is natural and typically won’t be cause for concern. But in case you get so fatigued that it’s hard to stay awake or perform your work effectively, she advises seeking guidance from your healthcare team.