Cookies.

Enjoying one small cookie is not a problem. "Most small (about 1 -2 ounces) cookies are around 200-250 calories, which is not bad if you eat only one -- but who can stop at one?" asks Tallmadge. The CD-sized cookies you commonly find at bakeries and restaurants pack a real caloric punch. At Dunkin' Donuts, the peanut butter cup cookie (4.5 ounces) has 590 calories, 29 grams of fat, and 13 grams saturated fat. At Panera, the shortbread cookie (2.5 ounces) has 350 calories, 21 grams of fat, and 12 grams saturated fat. So split it in half, or take along a 100-calorie pack of your favorite cookie.