The 10 Best Foods for Flat Abs

Soy and Apples

3. Soy

Soybeans are a great source of antioxidants, fiber, and protein. Plus, they're incredibly versatile. Snack on dry-roasted soybeans, toss shelled edamame into soups, and slip a spoonful of silken tofu into your morning smoothie. Liquid soy also makes a good meal replacement: A study from the Journal of the American College of Nutrition found that overweight subjects who drank a soy milkbased meal replacement lost more weight than those who consumed a traditional dairy-based diet drink.

Try for: Twenty-five grams of whole (not isolated) soy protein daily. A half cup of steamed edamame contains about 130 calories and 11 grams of protein. Four ounces of tofu (94 calories) contain 10 grams. Choose whole soy foods over products packed with "isolated soy protein" -- the latter may not provide all the benefits of whole soybeans.

4. Apples

A 2003 study in the journal Nutrition found that overweight women who consumed three apples or pears a day for three months lost more weight than their counterparts who were fed a similar diet with oat cookies instead of fruits. "A large apple has five grams of fiber, but it's also nearly 85 percent water, which helps you feel full," explains Elisa Zied, RD, author of So What Can I Eat?! (Wiley, 2006). Apples also contain quercetin, a compound shown to help fight certain cancers, reduce cholesterol damage, and promote healthy lungs.

Try for: An apple (or two) a day. A study published in the Journal of Agricultural and Food Chemistry found that the Red Delicious, Cortland, and Northern Spy varieties had the highest antioxidant activity.