5 Foods That Are Making You Sleepy

Here's one downside to a super-nutritious diet—when you decide to treat yourself, your body likely won't handle it very well. "Research indicates that our gastro-intestinal tract adjusts to what we eat," Politi says. "If you're sticking to a low-fat, low-sugar diet, you start to produce less of the gastric juices and enzymes that help digest sugar and fat easily." And that doesn't just spell digestive trouble; it can lower your energy afterward, too, likely more so than if you'd been eating less-than-superbly all along. Politi knows this firsthand. As a nutritionist, her own diet is the kind we all aspire to, and when she occasionally has a slice of cake at her office's monthly employee birthday parties, "I feel so lousy, like I need to take a nap immediately," she says.

Pick Yourself Up: No one's advocating total treat deprivation, but when you decide it's time for something more sugary or fattening than you typically eat, just be prepared for the slump that may follow.