Why You Crave Food After Mentally Taxing Tasks—And How Exercise Can Help
Could the solution to post-study session cravings be a 15-minute jaunt on the treadmill? According to new research in the journal Medicine & Science in Sports & Exercise, short but strenuous workouts may curb the hunger pangs that tend to follow challenging cognitive tasks.
For anyone who's ever ordered Domino’s after pouring over a spreadsheet, or wrapping up a complex report, the brain-fried binge is all too familiar. “Mental work utilizes the brain’s energy resources, and the brain then signals that it needs additional energy," researcher William Neumeier, PhD, a postdoctoral scholar at the University of Alabama at Birmingham (UAB), explained in an email to Health. "If food is available, the brain will use it to replenish energy. This could lead to overeating."
Neumeier and his colleagues suspected that physical activity might counteract that urge to eat: “Exercise, especially high-intensity exercise, can increase available energy in the body’s bloodstream, and promote satiety in the short term,” says Dr. Neumeier. The researchers hypothesized that the brain could replenish its energy deficit from a mentally-taxing chore by utilizing byproducts of exercise—primarily glucose and lactate—and halt cravings for more food.
To test their theory, they offered 38 healthy college students pizza (to see how much they ate under normal circumstances). On another day, they had the participants do 20 minutes of math and reading comprehension problems to tire out their brains. Afterwards, one group rested for 15 minutes while another group did interval training on a treadmill. Then the researchers served a pizza lunch, and tracked how many calories the volunteers consumed.
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The results lined up with what the researchers expected: “Mental work increased food intake by 100 calories, unless there was an intense bout of exercise in between,” study co-author Emily Dhurandar, PhD, an assistant professor in UAB’s Department of Health Behavior, said in an email. “Among those who exercised, there was no increase in food intake resulting from mental work.”
More research is needed to investigate the effects of workouts of varying types, lengths, and intensities. But the current findings might be helpful for workhorses looking to lose a few pounds. “People who find themselves hungry after completing mentally-demanding tasks should consider adding a bout of exercise to their schedule to help curb their appetite,” says Dhurandar.
So next time you finish a big item on your to-do list, try reaching for your running shoes before a bag of chips, and you may leave your cravings in the dust.