Recently I wasn't eating at the proper time and I often skipped meals. I was angry, stressed before taking my meal, and suddenly, I felt good after having my dinner. I have felt the same way many times.

Does food have that much effect on brain activity and emotions?


2 Answers 2


Part of the issue is maintaining blood-glucose concentration, which one doesn't always sense is crashing until it's already low and still crashing. As @BennySkogberg's answer implies, disruptions in the energy supply threaten cognitive function. This implies a loss of functional capacity and efficiency (which, when lacking, increase the probability of frustrating outcomes), as well as implying some disinhibition of impulses. Impulsivity relates to negative emotionality (including anger and stress), and interferes with attention. Reductions in the ability to focus attention on practical problems and address them planfully (problem-focused coping, which also relates to impulsivity, but negatively) would likely result; trouble envisioning solutions to problems might then decrease confidence and increase stress.

Another part of the issue is the homeostatic equilibrium between the sympathetic ("fight-or-flight") and parasympathetic ("rest-and-digest") nervous systems. Even before getting the post-digestion blood-glucose boost, one might achieve relaxation by simply having something to digest. Food in the stomach triggers parasympathetic activation, which facilitates relaxation and dulls the senses somewhat. An increasingly urgent lack of food in the stomach might (don't actually know) trigger the sympathetic system, as hunger implies some need to wake up and act assertively to correct it and prevent starvation. Sympathetic activation promotes aggression (and thus anger) and emotional arousal (and thus stress, which is negatively valent emotional arousal).

For a particularly extreme example of the effects of starvation, you might find the results of the Minnesota Starvation Experiment interesting. Food definitely has profound effects on psychological function; what you've felt may be a lesser shade of what these research participants reported after more prolonged deprivation. Also, FWIW, I've noticed the same effects you describe in myself and others I know well when starving (if only in the "first world problems" sense of being really hungry, having waited a couple hours too long to fix a meal). One doesn't need to prolong it to start seeing effects, especially when there's some violation of implicit expectations or customary levels of need satisfaction. Our bodies adapt to how well or how poorly we're fed on a regular basis, so those of us who are used to eating regularly may have exacerbated reactions to the rare violations of our habits, as our bodies haven't had the chance to adapt to deprivation gradually when the onset is sudden and unusual.

Edit: BTW, you might also find this question interesting (I've answered it similarly):
How is fasting related to insomnia?


There are numerous of commercials exploring this fact, and I can only listen to my eight-year-old daughter when she gets cranky from not eating her breakfast. If you don't eat or you eat wrong kind of food, your emotions will suffer.

Malnutrition and the Brain

Another way not eating can affect the brain is through malnutrition. The cells of your brain rely on energy from food just like any other cell in the body. Without the nutrition that food supplies, both your neural function and brain chemistry can be negatively impacted. This in turn affects just about every facet of your bodily function that the brain is involved in, including concentration, memory, sleep patterns, mood and your motor skills.

Source: How Does Not Eating Affect the Brain?


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