Is a “food coma” real?

We all know that feeling. We eat a big lunch (read: a gargantuan meal). We feel stuffed. Next thing you know we feel extremely tired. We want to take a nap but have an afternoon and evening of work ahead of us. We say to ourselves “I’m in a food coma.”

Here is the research I’ve done on what a “food coma” is and I also have an experiment you can try to see how to avoid one.

When you eat a meal two big things happen:

  1. Digestion: your body needs energy to digest all of this new food entering your body. Therefore more blood is sent to your digestive system to aid this process. More bood in the digestive system = less blood in the brain = you feel sleepy.
  2. Insulin release: The food you eat, especially if you are eating a lot of carbs will cause your insulin to spike. What is the purpose of insulin? Its job is to regulate the amount of blood sugar (aka glucose, which we get from carbs) in our body; it does this through a process called glycogenisis that causes your liver to convert glucose in to glycogen and it forces our muscle cells and fat tissue cells to take up glucose from the blood, thus decreasing blood sugar. Carbohydrates cause your body to release insulin, which removes all amino acids—except tryptophan—from your blood. That means that tryptophan has no competition and can enter the brain easily, boosting serotonin levels. Serotonin is responsible to tell your brain to go to sleep. Hence you feel sleepy. Food coma is real!

The reason why you don’t feel sleepy when you aren’t fasting (or eating 6 smaller meals throughout the day for example) is because your body is always “on” in terms of having insulin in the body so this insulin level becomes a new “baseline” if you will. Every time you eat a small meal with carbs, more insulin is released in to the bloodstream. If you are fasting, or go some time between meals and then eat a lot of carbs this baseline is no longer there so boom, the above food coma can happen.

Figure 2. Tryptophan crossing the blood-brain barrier with the help of carbs and being blocked without them. Source: BBC

Therefore, one way that has worked for me to avoid a food coma is to break your “fast” (or if you’re eating a bigger meal in general after having not eaten in a while) with protein, fats and a tiny bit of carbs (or no carbs at all) and see how you feel.

Digestion will still require energy but by limiting the spike of insulin, you might find that your afternoon lunch does not lead to grogginess and tiredness in the afternoon.


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