Food is fuel. Each calorie we ingest gives us its own little burst of energy, powering our body’s innumerable functions—from large-scale actions like running and weightlifting to the small-scale repair and creation of new cells. We even use energy from food to digest food. (How meta is that?)
So, if food is our body’s source of oomph, why is it we so often feel tired after eating? We all know the telltale signs of an afternoon slump or post-dinner “food coma”—but sometimes we may even notice that a snack slows us down instead of picking us up.
We asked the experts about this frustrating conundrum. Here’s why your energy might feel zapped after eating, plus strategies for preventing the plummet.
- ABOUT OUR EXPERTS: Alyssa Simpson, R.D.N., C.G.N., C.L.T., is a registered dietitian and owner of Nutrition Resolution. Melissa Groves Azzaro, R.D.N., L.D., is a registered dietitian who specializes in hormones.
Your Blood Sugar Has Dropped
The body’s reaction to a high intake of carbs is a veritable rollercoaster that can ultimately leave you feeling wiped out. “When you consume foods rich in carbohydrates or sugars, your body quickly converts them into glucose, causing a spike in blood sugar levels,” explains dietitian Alyssa Simpson, R.D.N., C.G.N., C.L.T., owner of Nutrition Resolution. “This prompts your pancreas to release insulin to metabolize the sugar.”
Read More: 8 Supplements That Support Healthy Blood Sugar
Though this process is necessary, if insulin levels rise rapidly, a steep drop in blood sugar (known as reactive hypoglycemia) can follow. “This resulting low blood sugar can hinder brain function and concentration, exacerbating feelings of tiredness and lethargy after consuming a high-carbohydrate or sugary meal,” Simpson says.
The Solution
Heading off a blood sugar crash doesn’t mean never eating carbs. Instead, it may be a matter of what you eat with your carbs. To slow down glucose absorption, try pairing high-carb foods with a source of protein and/or healthy fat. (Think peanut butter with your crackers, chicken with your rice, or fish with your pasta.) Go even further by swapping out refined-carb foods like white bread or sugary cereals with fiber-rich whole grains. These tweaks can all help keep blood sugar from spiking—and eventually crashing—after you chow down.
Your Circadian Rhythm Is Responding to Stress
Some level of post-meal tiredness is a normal part of the body’s natural circadian rhythm. That said, energy that dramatically tanks after meals—especially later in the day—might indicate a stress response by your circadian rhythm.
Here’s how it works: About two hours after you wake up, your cortisol (stress hormone) levels reach their peak, making mid-morning the time of day most people have the most energy, says “The Hormone Dietitian” Melissa Groves Azzaro, R.D.N., L.D. “If mornings are particularly stressful and cortisol jumps too high, you may ‘use up’ your daily cortisol too soon and find your energy lagging in the afternoon,” she explains. As a result, you may find yourself wiped out and desperate for sugar or caffeine not long after lunch.
The Solution
If your post-meal energy dips are more like cannonballs, take stock of your mornings. Is this part of the day usually a stressful time? If so, managing stress earlier in the day might leave you with more energy later on. (These natural tips for relieving stress can help you get started.)
You Ate Too Much
It’s not just an epic, multi-course Thanksgiving feast that can leave you drowsy in the hours that follow. Any larger meal can contribute to feelings of tiredness. “Digesting all that food takes a lot of energy, which can leave you feeling drained as your body diverts resources to the task,” Simpson says. A surprising 10 percent of the calories we take in are used for digestion alone!
Interestingly, spikes in insulin caused by overeating can make matters worse. “[This] can make you feel sleepy by helping your body absorb tryptophan, a building block for sleep-related chemicals like serotonin and melatonin,” explains Simpson.
The Solution
The surest route to preventing fatigue after a heavy meal? Eat smaller, balanced portions. You can do so by measuring out the amount listed as the serving size, using smaller dishes, or switching from a couple of big meals to several smaller mealtimes spread throughout the day. Not only will your digestive system have less to tackle, but your insulin won’t rise as high and trigger sleep-inducing chemicals.
You’re Not Getting Enough Sleep
Obviously, not getting enough sleep can leave you tired the next day. But what might not be obvious is how it affects food-related fatigue. “Getting less than seven hours of sleep at night can make us feel fatigued the next day—and it also impacts what we crave and eat,” says Groves Azzaro. “Sleeping for less than seven hours has been linked to higher risk for insulin resistance—and even one night of poor sleep can increase both cravings for and consumption of sugar and carbs.”
Plus, lack of sleep leads to increased ghrelin, a hormone that increases our hunger levels, Groves Azzaro points out. In all, falling short on shut-eye sets us up for overeating—and specifically for eating the types of foods that leave us even more tired after eating. (Now that’s just not fair.)
The Solution
Getting enough sleep at night is no small task, but doing so comes with a host of benefits. If daytime fatigue is a persistent problem—whether after eating or all throughout the day—it’s smart to tend to your nighttime routine.
Besides creating better sleep hygiene with tactics like keeping a consistent bedtime and turning off devices an hour before turning in, consider using food to set the sleepy mood. Beverages like chamomile tea and tart cherry juice have been linked to better sleep, while pistachios, almonds, and walnuts all contain the sleep-promoting hormone melatonin. Adding these close to bedtime might help you nod off easier, ultimately setting you up for a better food-energy cycle.
Your Hormone Levels Are Off
An intense bout of fatigue after mealtimes could also signal underlying hormone problems. “Fatigue after eating is a red flag for me that the person may have insulin issues,” says Groves Azzaro. While reactive hypoglycemia can happen to anyone, when issues with the hormone insulin pop up, it may indicate insulin resistance. With this condition, insulin doesn’t properly usher glucose into your cells. Since glucose is the body’s primary energy source, you might not reap the invigorating benefits of your food if it’s not reaching your cells appropriately.
Read More: Balance Your Hormones Naturally With These Supplements
Similarly, low estrogen or problems with thyroid hormones can leave you sleepy any time of day, including after a snack or meal.
The Solution
Can’t-get-off-the-couch levels of fatigue (post-meal or otherwise) aren’t something to ignore. If you’re consistently tired after eating and can’t pinpoint why, consult with your doctor so they can perform tests to assess your hormone levels.