Debunking a myth: Why we have a food coma after a big meal?

Guys sleeping after having a party at home. Image credit George Rudy via  shutterstock.


Recalling your last big meal, after that last mouth of food, you just sank into an unmanned couch with your popping straight belly. You couldn’t keep your eyes open and stop the extreme lethargy and sleepiness anymore. In fact, what you’re experiencing is called food coma, which is referred as postprandial somnolence by scientists.

The popular Australian coffee culture had made me doubt that food coma might be ‘an epidemic’ only suffered by Chinese. What? Are you kidding me? Recently, an Australian told me she often felt sleepy after lunch, she might get food coma. To be honest, it was such a relief to hear it, it’s not just Chinese.

Food coma as a normal phenomenon is not only a gossip topic, but also as a trouble-maker which affects us. Most friends think food coma is caused by unequal blood distribution during digestion, but others said food coma caused by different diet habits. So, what is correct answer? Today, let’s debunk the myth.


Q1: Does our blood leave our brain after a meal?


It has been no scientifically proven that food coma is caused by moving blood flow from our brain to our mesenteric vessels (a tube-shape conditional blood supply to our small and large intestines). In 2003, researchers investigated the blood flow changes in twenty healthy people’s during eating. However, the results showed that there was no decline in brains’ blood flow during digestion. The volume of blood flow increases in intestine tract, but it is not responsible for food comas.


Q2: Does the thanksgiving turkey make Americans drowsy?


Roasted turkey. Image credit Bochkarev Photography via shutterstock.


The question why we are likely to feel extremely sleepy after a thanksgiving meal has obsessed Americans for years. A popular explanation is that turkey includes an amino acid, tryptophan, which induces food comas. But the truth is, any other meat, such as chicken and beef has as similar volume of tryptophan as turkey. In other words, turkey is not likely to effect on your food comas.

Remember, except the turkey, rolls, pumpkin pie, potatoes and stuffing are often added as additional ingredients. That means an enormous amount of carbs are ingested. Scientists have found that the consumption of high glycemic indexes can accelerate people go into sleep onset.


Q3:  Is it useful to change what you’re eating everyday?


As a Chinese, I like eating rice or noodle as main meals every day. But thinking about how food comas faze my life, shall I say goodbye to my favourite rice and noodle?  What if an Australian would stop drinking coffee or eating mashed potato? It doesn’t bear thinking about.

One interesting study points out the limitations of the current food comas’ hypotheses and indicates that after a meal, there is ‘communication’ between our gut and brain. It seems like before we finish a team lunch, chatting with colleagues is indispensable. Our gut digests food and sends out a signal like “I am full and ready to have a nap. Please approve.” to our brain. When the signal arrives the ventromedial hypothalamus (“satiety centre”), another part of brain, the lateral hypothalamic area which controls (“hunger centre”) is going to shut down. The “hunger centre” is charge of reducing sleepiness and promoting arousal. It is more likely to induce drowsiness, when the “hunger centre” is inhibited due to overeating, drowsiness is likely the result.


Q4: Perhaps Dr. Darwin knows why food coma occurs?


Dr. Darwin developed a famous theory, Darwinism, which is about biological evolution through natural selection. In human evolution, sleep value is an  open question. Some scientists think food comas may relate to energy recovery and gastrointestinal data gain.

Food coma may be tiny but it is complicated, scientists are still trying to solve this enduring mystery.

PS: Today, I have tried to just eat a box of boiled vegetables (regular size) as my lunch, but I still got a food coma after eating. Tomorrow I will try running after lunch, any other suggestions?


Further readings on food coma:


Give a pillow to a Chinese, he or she can sleep on a desk

How to avoid food coma from the art view

4 Responses to “Debunking a myth: Why we have a food coma after a big meal?”

  1. Ye Zheng says:

    Thanks Bianca, i am glad to know you like this blog. Hope food coma just likes an afternoon joke and doesn’t affect us to much.

  2. Bianca Fato says:

    The title instantly made me want to read this post! Who knew that it is actually a thing? I like how you structured the post to answer questions and develop the sequence of ideas, good job!

  3. Ye Zheng says:

    thanks pooja 🙂 that’s what i want to do.

  4. Pooja Venkat says:

    hehe. I would suggest you to just take a nap.

    Just to point out, both the links given at the last points out to the same website.