Reduced or zero-fat foods can be sneaky little devils. Sure, they contain less fat than their regular-fat counterparts, but they’re still likely to increase your calorie consumption overall. Why? Because it’s all about the eater’s perception. When people are given foods marked as low fat, they chow down 25-44 percent more calories than they do when it’s a full-fat label. They also underestimate the total calories they’re consuming because—dieters, cover your ears—most reduced-fat foods are only about 11 percent lower in calories than their alternatives. Don’t believe it? The proof is in the peanut butter, for example: Reduced-fat peanut butter has almost as many calories as regular peanut butter! So watch those labels carefully for both fat and calorie levels. Some snacky foods are wolves in sheep’s clothing.