We all know that lethargic feeling after eating a huge meal (hello holidays, birthday celebrations and boredom). But what's also inevitable is the ravenous appetite the next morning.
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This appetite spike can cause you to overeat first thing in the day and then hinder your productivity and energy levels for the next couple of hours.
But there's actually a scientific reason for the surge in appetite, and it mostly has to do with your blood sugar and hunger hormones. Here's what's going on in your body when you eat a big meal at night and wake up hangrier than ever.
Your Blood Sugar Spikes
When you eat a large meal for dinner, your blood sugar spikes, which then leads to a subsequent drop that can cause you to wake up with a rumbling belly and some major cravings.
Indeed, researchers found that blood glucose levels were significantly elevated after a late-night meal compared to after breakfast, according to a small November 2018 study in Nutrients.
"This is likely due to overeating and eating fewer healthy foods that are high in sugar, which causes your pancreas to put out too much insulin, a hormone that helps our cells take up the sugar from our blood," says NYC-based dietitian Amy Shapiro, RD, CDN.
If you have too much insulin circulating in your blood (like after a big meal), your blood sugar levels drop dramatically, which could cause you to feel tired or lightheaded. And that's why you might find yourself digging into everything from your kitchen fridge or pantry.
The November 2018 Nutrients study also found that the participants' levels of incretins (glucose-lowering hormones) were higher in the morning than in the evening. "This could mean that the body doesn't use the energy for a late-night meal as effectively as it does from early day meals," says dietitian Sofia Norton, RD.
Celebrations, holidays and large dinners usually involve overeating high-carb foods, such as mashed potatoes, dinner rolls, rice, cake and cookies, which are all quickly digested and are high on the glycemic index (GI). High-GI foods cause your blood sugar to spike and then drop, leading to hunger the next day, Shapiro explains.
Stick to smaller portions of the high-GI foods and include more low-GI foods such as whole grains in your menu.
The excess sugar and sodium in your nighttime meal can make you dehydrated in the morning, beyond the normal dehydration that's a result of hours of sleep.
And the brain can easily mistake thirst for hunger. "Before you eat, gulp some water," Shapiro says. A glass or two in the morning before breakfast can help your hunger dissipate.
You Might Not Have Slept Well
"When we go to sleep with a full stomach, the body needs to use energy to digest the food we ate and, therefore, it can't fully relax and restore while it works on breaking down the nutrients we've eaten," Shapiro says.
This can make it challenging to fall asleep and stay asleep throughout the night. But sleep helps balance our hormones, like the hunger-increasing hormone ghrelin and hunger-suppressing hormone leptin. So, when you're low on shut-eye, your hormones become imbalanced.
Ghrelin (which makes you hungrier) spikes while leptin (which decreases appetite) becomes suppressed, Norton says.
"Additionally, going to sleep too full can lead to acid reflux or a GERD flare-up, which can keep people awake and disrupt sleep," Shapiro says.
"Research shows we reach for high-sugar foods in order to give us a boost in energy when we're tired," she says. Plus, it's easy to drink excess coffee to try and wake up, which can lead to more dehydration and affect your sleep the following night — especially if you drink it too late in the day.
So, Here's What to Do Right After That Big Meal
Try these tips if you feel like you'll still be asking yourself, why am I always hungry after eating a big dinner?
Give Yourself Time to Digest
"I would try to stay awake for at least two hours after your meals to allow yourself to digest before laying down," says Shapiro. This helps prevent too much acid reflux and helps aid digestion.
Take a Walk
"I would also recommend going for a walk if possible to help with digestion," she says. In fact, walking after eating a meal helps speed up gastric emptying while digestive aperitifs do not, per a small March 2008 study in the Journal of Gastrointestinal and Liver Diseases.
Get a Good Night's Sleep
Try to make yourself as comfortable as possible for the night by cooling down your bedroom, turning off the lights, using earplugs if you live in a noisy street and minimizing screen time, Norton says.
What to Do the Morning After a Big Meal
"I would recommend starting with a glass of water and then serving yourself a balanced and healthy breakfast," Shapiro says.
A solid protein- and fiber-rich breakfast is a cup of Greek yogurt sprinkled with 2 tablespoons of flax meal and topped with a handful of fresh berries. You can also try porridge, banana and peanut butter, and baked eggs in avocado, Norton recommends.
Keep it nutritious and light, and then see how you feel a bit later. And remember that eating your normal a.m. meal will likely satisfy you — even if the portion seems smaller than you think you need. The key is to wait 20 minutes or so before serving yourself a second breakfast.
And next time you find yourself headed to a big dinner, remember to include protein, healthy fats and fiber on your plate.
"Making sure you balance out your meal no matter how large it might be and to limit your sugar consumption," Shapiro says. This will slow the sugar fluctuations in your body, so you won't wake up as hungry as you would without those stabilizing vitamins and minerals. "Pick only one dessert, and take the others home for another day," Shapiro says.
- Nutrients: "Effects of Meal Timing on Postprandial Glucose Metabolism and Blood Metabolites in Healthy Adults"
- PLOS Medicine: "Short Sleep Duration is Associated With Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index"
- Journal of Gastrointestinal and Liver Diseases: "Postprandial Walking but Not Consumption of Alcoholic Digestifs or Espresso Accelerates Gastric Emptying in Healthy Volunteers"