Why do I feel calmer after eating? (The brain gut relationship)

Have you ever experienced feeling calmer after eating? Maybe it’s not “in your head.” Maybe there’s something real going on. Many feel more relaxed after eating. As a dietitian and a human with lived experience, I think about this a lot.

One theory is that there is not enough blood in the body to power everything at once. The body has two separate states - the sympathetic nervous system (the stress state), and the parasympathetic nervous system (the relaxed state). The stress state happens when you are motivated, focused, running, exercising, scared, worried, or anxious. The relaxed state happens when you are eating, sleeping, walking, cuddling, watching a relaxing TV show, etc. The body only has about 5L of blood - this is only 2 and a ½ 2L milk cartons. It cannot power your body for action and power your body for digestion at the same time. This blood is allotted depending on which type of nervous system is activated.

When you eat, the body is in a parasympathetic (relaxed) state. The body is settled, away from risks and ready to refuel. When food enters your system, the blood goes to the stomach and away from other organs. It does this by relaxing the blood vessels, allowing the blood to fill and provide nutrients. Activities that promote the stress (sympathetic) state are not well tolerated at this time. This is also why you get cramps while exercising right after eating.

The second reason is the stimulation of the vagus nerve. The vagus nerve is involved in parasympathetic activation. Again, this makes you feel relaxed. The vagus nerve has been the subject of a lot of research in the last few years. Psychologists are working to uncover how vagal nerve stimulation can help improve states such as anxiety. This can translate to food and nutrition as well. The stomach has nerves that detect and communicate stretch. When the stomach fills up, it stretches. The stretching then stimulates the vagus nerve to produce a calming effect.

The third reason is related to stress hormones. One key stress hormone called cortisol, is responsible for waking you up in the morning. Cortisol is a great hormone in moderate and timely doses. If your body makes too much for too long, it may not be the healthiest. It’s also related to hunger cues and making you hungry. The act of eating dampens this hormone causing the stress response to go down. Cortisol may be involved in making you “hangry”.

If you feel full for much longer than normal, and this is accompanied by other symptoms such as pain and nausea, it could be a sign to seek medical attention. There’s a syndrome called gastroparesis, which can be a result of uncontrolled diabetes. This is where the nerves that control stomach emptying stop working properly. The stomach must mix and grind food, and then release about 1/10 of a mL into the intestine at a time. This involves a complex orchestra of nerves. Much like a symphony, the nerve signals have to coordinate to get the desired result.

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AI may be used in some writing for sentence structure and paragraph organization. However, all ideas are based on my own clinical judgement and evidence-bases such as scientific studies and professional guidelines.