Is This Why You're Gaining Weight?

The situation: You eat no differently than your friends, but you're the only one shopping for bigger pants.

Why you're gaining: Look at your stress levels. A small study in Biological Psychiatry suggests that stressed-out women who eat the same high fat foods as non-stressed women may be more likely to pack on pounds. Researchers had subjects eat the equivalent of a fast food meal and found that women who'd experienced a stressor (the most common: interpersonal drama, like conflicts with friends, family and coworkers; work stress) in the 24 hours prior to eating burned fewer calories at rest afterward—about 104 calories to be exact. Over a year, the researchers say that could add up to almost 11 new, unwelcome pounds.

How to stop it: Keep healthy food (not the high-fat kind that the study focused on) handy for when stress inevitably starts to hit the fan, as it's less likely to lead to weight gain.