Steak

Beef has a rep as a diet buster, but eating it may help you peel off pounds. In a study published in The American Journal of Clinical Nutrition, women on a diet that included red meat lost more weight than those eating equal calories but little beef. "The protein in steak helps you retain muscle mass during weight loss," says study author Manny Noakes, Ph.D. Try to consume local organic beef; it's healthier for you and the environment.

Eat more Grill or broil a 4-ounce serving of top round or sirloin; slice thinly to top a salad, or mix with veggies for fajitas.

Eggs

Dig in to eggs, yolks and all: They won't harm your heart, but they can help you trim inches. Women on a low-calorie diet who ate an egg with toast and jelly each morning lost twice as many pounds as those who had a bagel breakfast with the same number of calories but no eggs, a study from Louisiana State University in Baton Rouge reports. "Egg protein is filling, so you eat less later in the day," says David Grotto, R.D., author of 101 Foods That Could Save Your Life

(Bantam).

Eat more Omelets and scrambles are obvious choices, but if you can't cook before work, bake a frittata on Sunday; chill it and nuke slices for up to a week. An easy recipe: Vegetable Frittata.

Kale

Long sidelined as a lowly garnish, this green belongs center stage on your plate. One raw chopped cup contains 34 calories and about 1.3 grams of fiber, as well as a hearty helping of iron and calcium. But kale's earthy flavor might take some getting used to. Spinach, another nutrient powerhouse, is a milder-tasting option.

Eat more Mix chopped raw kale into cooked black beans, says Jennifer Iserloh, founder of Skinny Chef Culinary Ventures, in New York City. Or slice kale into thin strips, sauté it with vegetable broth and top with orange slices. Make it a meal by tossing the mix with quinoa.

Oats

"Oatmeal has the highest satiety ranking of any food," Grotto says. "Unlike many other carbohydrates, oats—even the instant kind—digest slowly, so they have little impact on your blood sugar." All oats are healthful, but the steel-cut and rolled varieties (which are minimally processed) have up to 5 grams of fiber per serving, making them the most filling choice. Instant oats contain 3 to 4 grams per serving.

Eat more "Instead of using breadcrumbs, add oats to meat loaf—about 1 cup for a recipe that serves eight," Iserloh recommends. Or try her recipe for turkey and oatmeal meatballs.

Lentils

Lentils are a bona fide belly flattener. "They're high in protein and soluble fiber, two nutrients that stabilize blood sugar levels," says Tanya Zuckerbrot, R.D., author of The F-Factor Diet (Putnam Adult). "Eating them helps prevent insulin spikes that cause your body to create excess fat, especially in the abdominal area."