3. Nut Butters
Why they make you skinny:
Research has shown that people who eat nut butters often weigh less than those who shun them. It's likely that the combination of protein, fat and fiber keeps you full, so you'll eat less overall.
Whole nuts are effective, too: Purdue University researchers found that people who added peanuts to their diet for 19 weeks boosted the amount of calories they burned at rest by 11 percent. Why? The unsaturated fat in peanuts and nut butters burns faster than other fats.
How to use them:
Nut butters add flavor to Asian noodles, satays or dipping sauces, or you can use them as a spread for your morning muffin. Chunky varieties are better, since they have more fiber than creamy versions. But a little goes a long way, says New York-based nutritionist Bonnie Taub-Dix, R.D. "The ideal amount is one to two tablespoons, not the whole jar." Use natural versions that are free of added oils and hydrogenated fats.
When Good Fats Go Bad
All fats contain nine calories per gram. To get weight-loss benefits, you have to substitute these for fat that's already in your diet, not tack them onto what's on your plate.