If a good meal leaves you ready for a nap, you’re not alone. Fatigue after a meal is a surprisingly common phenomenon—and we’re not just talking about how you feel after Thanksgiving dinner. From hormones to food sensitivities, there are a number of potential culprits for that afternoon slump. Luckily, there are also a few workarounds.
5 causes of post-meal fatigue.
First things first: Hormones play a major role in post-meal tiredness. “After we eat, the food substrate ignites a sequence of secretion of hormones that produces a change in our biochemistry,” says Kent Sasse, M.D., double board-certified surgeon and author.
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“Insulin secretion goes up to help us process the new fuel hitting our system, and this hormone helps blood sugar enter into the cells and tissues. But it’s also associated with a rise in a whole cascade of other hormones, some of which act on the brain to make us drowsy and feeling fatigued,” he says. “Some of these circulating hormones act at the muscle level and can also create a sense of muscle tiredness.” So that’s why you might be feeling exhausted clear down to the bone.
When you pair this biochemical change with any of the following, it’s pretty easy to see how it could lead to a post-meal slump:
1. What (and how much) you’re eating.
A high-carb meal, in particular, triggers a rise in insulin. “When these insulin levels peak after eating, this can lead to a crash in our blood sugars—leading, understandably, to that all-too-familiar post-lunch slump—a foggy brain and tired body,” says Uma Naidoo, M.D., nutritional psychiatrist, professional chef, nutrition specialist, and author.
A big meal is also going to hit you harder than a smaller meal. “Less food energy substrate equals less insulin and hormonal response, which means fewer side effects,” explains Sasse.
2. Unknown allergies and undiagnosed conditions.
That unpleasant, draining “brain fog” after a meal with gluten may be pointing to a condition like celiac disease, particularly if it’s paired with uncomfortable GI symptoms, headaches, or migraines. Then again, you may just be sensitive to gluten. “Even in folks without celiac disease, research is finding that having a foggy mind, headaches, or body pains after eating gluten may indicate the presence of non-celiac gluten sensitivity,” notes Naidoo.
There could also be other undiagnosed conditions that are making that post-lunch slump worse. If feeling tired after every meal (or all the time) is pretty typical for you, it’s a good idea to speak with your doctor.
There is evidence linking random mealtimes with increased fatigue, and one study found that eating a large lunch after skipping breakfast actually contributes to less blood flow in the brain. Not only does that make it harder to focus, but it can also lead to fatigue. “Without the ample flow of blood, the brain conserves its essential functions, and we may become more drowsy,” says Naidoo. So if you omit breakfast as part of intermittent fasting, for example, consider slowly transition back into eating with a mini-meal (you can learn all about that technique here).
4. Including alcohol in the mix.
Telltale fatigue is even more noticeable if you’re drinking alcohol with your meal. “While a glass of fine wine may complement your meal, alcohol functions as a central nervous system depressant,” says Naidoo. “As such, having a bit too much to drink may contribute to feeling fatigued after a meal.”
If you’re already dragging, a meal has the potential to make you feel even more exhausted. Naidoo explains that it’s because both your ability to metabolize sugars and even your appetite could be impaired.
“With sleep deprivation, your body and brain are just waiting for something like this to push them into full-on nap mode,” agrees Sasse.
5 ways to prevent post-meal fatigue.
Identifying what may be causing you to crash and burn after a meal is one thing, but avoiding it is another. Fortunately, there are simple steps you can take to help keep your energy levels high and minimize those sleepy feelings after you eat:
1. Manage your macro balance.
“A person can reduce the feeling by reducing the most potent stimulator of insulin secretion after meals, namely sugar,” says Sasse. “Avoiding the bread, chips, crackers, sugary beverages, and ice cream dessert means there is a whole lot less insulin secretion from the meal, and a whole lot less of the big swings in blood sugar and the related family of hormones.”
Naidoo advises adjusting your meal composition—specifically, decreasing carbs and including more protein- and fiber-rich foods. “In doing so, we optimize nutrients that keep our blood sugar levels steady: Both protein and fiber are known to improve glycemic control. Also a fiber-rich meal means extra love for your gut, as our gut microbes thrive on fiber.” There’s also evidence that a veggie-rich diet with ample amounts of healthy fats reduces post-meal sleepiness.
And here’s Naidoo’s pro tip: “Research suggests that including vinegar in carbohydrate-rich meals may improve glycemic control and, subsequently, prevent post-meal fatigue.”
Sleep deprivation wreaks havoc on the metabolism, but there is good news. “Just one night of adequate sleep can reverse the negative effects,” says Naidoo. And in a pinch, a post-lunch nap can work wonders.
3. Stick to regular mealtimes.
There’s a lot of contradictory information out there when it comes to diet, but one thing is clear—eating regularly matters. “The body performs best while operating on a consistent schedule with sleep, wake, and scheduled mealtimes,” says Naidoo. “This encourages balanced energy, constant blood to nourish the brain, and appropriate hunger cues—all contributing to optimal alertness and mental clarity.”
In other words, maintaining regular mealtimes can help you stave off those post-meal yawns.
Regular exercise has a laundry list of benefits, and chief among them is that signature energy boost. Commit to moving your body regularly, shooting for 30 minutes every day. But keep in mind, even a post-lunch lap or two can be enough to keep your energy levels high.
If you’re regularly fighting to keep your eyes open after a meal, you aren’t alone, and a little detective work can be a game-changer. Naidoo notes that one of the pillars of nutritional psychiatry is body intelligence, which simply means paying attention to your body’s cues before, during, and after meals. Sounds simple, but we’re likely all guilty of multitasking when we eat. Eating mindfully gives us the opportunity to really assess what’s going on. What makes us feel good? What isn’t serving us? What might have led to this post-meal crash, and what steps can we take to avoid that next time?
“If you’re unsure where to start, focus on adding colorful, fiber-rich, and antioxidant-packed vegetables and fruits to your plate,” says Naidoo. “The added nutrients fend off fatigue, and fiber nourishes the gut, which, in turn, encourages a healthy brain.”