Glucose is the only form of energy that can cross the blood-brain barrier

Resch also warns against skipping meals. That habit can backfire, she says. When the brain is deprived of fuel, it calls for more to be delivered, ASAP. That translates to wanting carbohydrate-heavy foods, since those convert quickly to glucose (blood sugar), which is the body’s main energy source.

“Glucose is the only form of energy that can cross the blood-brain barrier”—that is, permeate from the bloodstream into the brain—“so if you deny your body food, you will go after carbs in a big way,” says Resch.

Therefore, she advises, don’t go more than four hours without eating.

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Inadequate sleep causes changes in the hormones that regulate appetite: ghrelin, which is released by the stomach and stimulates appetite, and leptin, which is produced by fat cells and inhibits appetite.

“Lack of sleep suppresses hormones linked to regulating appetite … so you don’t have a filter telling you to stop eating,” says Su-nui Escobar, RD. “You are hungrier all the time.”