This ‘rest and digest’ theory may explain why 'food comas' happen
It can strike anywhere, at any time.
Maybe it happens after eating a massive, juicy burger. Or after you went back to the hotel buffet for another plate (worth it!). And, yep, you probably remember it happening at Christmas, after sitting down and feasting on a roast dinner and all the trimmings: it’s the dreaded food coma.
As soon as you start to feel it happening, it’s too late — there’s nothing you can do to prevent the combination of bloating and fatigue. Once that heavy, tired feeling sets in, your food coma is already in full swing. Or is it?
Whether you’ve had more than a few food comas yourself or you’ve only heard of them, you can’t deny that they’re unpleasant. While I’m all here for a cheeky afternoon good nap, it’s better to take one on your own terms (not just because you went for an extra helping of dessert!).
As infamous as food comas are, there are also plenty of myths around them. Despite what you might have heard, they’re not caused by tryptophan-filled turkey or blood flow that’s diverted from your brain, confirms Dr Samantha Nazareth, a board-certified gastroenterologist. BTW, tryptophan is an amino acid found in some foods that your body uses to make hormones like serotonin and melatonin, both of which influence the sleep cycle.
‘The brain blood flow,’ she explains to Women's Health, ‘is highly, highly regulated and just doesn't shut down for any reason.’ She also adds that the tryptophan theory was debunked once research showed that fatty foods can cause even more sleepiness in some cases.
So, what are food comas, and why do they happen? Here’s everything you need to know, including how to prevent them:
What is a food coma?
First thing’s first: The medical term for a food coma is actually postprandial somnolence, Nazareth says. ‘The direct translation from that is after-meal sleepiness.’ Symptoms of a food coma include sleepiness, feeling groggy, or wanting to take a nap, she explains.
Basically, it’s an energy drop that kicks in after a meal — and the reasons behind that drop are based on your body’s biology (more on that in a sec).
What are the causes of a food coma?
Nazareth explains that doctors have two working theories about why food comas happen:
Theory one: Eating a meal filled with high-carb and high-sugar foods (think white rice, and white bread) causes your blood sugar to spike. The resulting crash can then lead to a food coma.
Theory two: You've heard of ‘fight or flight,’ but Nazareth says there’s another ‘switch’ in your body that controls ‘rest and digest’. When you eat a large meal, the ‘rest and digest’ switch flips on and stimulates your vagus nerve, which is responsible for regulating your emotions. From an evolution standpoint, you wouldn’t want to waste a good meal by fighting or fleeing. So instead, your vagus nerve communicates to your body that it’s time to rest.
Portion size also matters, Nazareth notes, especially when it comes to theory one. So eating high-carb and high-sugar foods might not necessarily trigger a food coma unless you eat a lot of them at once.
And in theory two, the vagus nerve responds more to a gigantic meal rather than a specific kind of food.
How do you prevent a food coma?
Now that you (kinda) have an idea of why some meals might trigger an intense need for a nap, you might be wondering how to stave that feeling off. Luckily, there are plenty of ways to prevent a food coma from happening in the first place. Some easy strategies include:
Maintaining a regular sleep schedule. ‘You don’t want to eat when you’re sleep-deprived,’ Nazareth says, especially a large meal. A lack of sleep can majorly contribute to a food coma, so make sure you’re getting those eight-ish hours
Eating smaller meals. Since portion size is a big factor, Nazareth recommends limiting the size of your meals to prevent that tired, groggy feeling from popping up. Not sure how much is too much? According to the NHS, A portion is: a fist size of potatoes, bread, pasta or other starchy carbohydrates; a palm size of meat/fish or poultry; two handfuls of vegetables or salad; a cupped-handful of fruit; top of your thumb size of oil or fat spread.
Staying active. ‘Any activity increases alertness,’ she says. ‘It’s also good for digestion.’ She suggests taking a walk after you eat to get your body moving again.
Balancing macronutrients. You don’t have to avoid carbs altogether, Nazareth explains. Just add some protein, healthy fats, and veggies to round out your plate.
Timing your meals right. Eating a late dinner (defined as one hour before bedtime) might actually help you sleep better, at least at the beginning of the night, according to one study in the Journal of Nature And Science Of Sleep. Just beware that eating at night may also have its cons — another study in the journal, BMC Public Health found that late dinners can put you at a higher risk for diseases like high blood pressure and obesity.
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