Melissa Punch

Chances are that at some point this week, you'll get home from work, tired and hungry, and feel very, very tempted to flop down in front of the TV instead of putting on your gym clothes. At least I know that's usually in the cards for me. And I now know what I'll do when I'm in such a pickle: I'll have a sweet snack.

Recent research has found that in order to make any good decision at all—whether it’s about going to the gym, holding your tongue, or avoiding a shoe splurge—your brain literally requires energy, which it gets from glucose. “Self control is like a muscle,” says Roy F. Baumeister, PhD, professor of social psychology at Florida State University and co-author of the book Willpower: Rediscovering the Greatest Human Strength.

“After you do something—anything—that uses self-control, the muscle gets tired, and if a second task requiring self-control comes along, you’ll do worse on it. A dose of glucose seems to replenish people’s willpower.” After a day of diligence in the office, your brain might need a hit of sugar to make its next good decision. Alas, the optimal way to put this info to good use is not to eat a cupcake (which may give you a quick hit of mental strength—and then a crash from the sugar high), but rather to stick to more natural forms of sugar, like those found in fruit.

“You want the kind of fuel that will burn over a longer period of time,” says Baumeister. “Protein combined with natural sugar is an excellent choice.” Try an apple with almond butter or yogurt and berries for optimal restraint.