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."

Eat more There are many varieties of lentils, but red and yellow cook fastest (in about 15 to 20 minutes). Add cooked lentils to pasta sauce for a heartier dish, Zuckerbrot suggests. "Their mild flavor blends right in, and because they're high in protein, you can skip meat altogether."

Goji berries

These chewy, tart berries have a hunger-curbing edge over other fruit: 18 amino acids, which make them a surprising source of protein, says chef Sarah Krieger, R.D., spokeswoman in St. Petersburg, Florida, for the American Dietetic Association. (They also have more beta-carotene than carrots.) Snack on them midafternoon to stay satisfied until dinner. The calorie cost? Only 35 per tablespoon.

Eat more Mix 1/4 cup of the dried berries (from health food stores) with 1/4 cup raisins and 1/4 cup walnuts for a nourishing trail mix. Or for dessert, pour 1/4 cup boiling water into a bowl with 2 tbsp dried berries; let sit 10 minutes. Drain, then spoon over 1/2 cup lowfat vanilla frozen yogurt.

Wild salmon

Not only do fish fats keep your heart healthy, but they shrink your waist, too. "Omega-3 fatty acids improve insulin sensitivity—which helps build muscle and decrease belly fat," Grotto explains. And the more muscle you have, the more calories your body burns. Opt for wild salmon; it may contain fewer pollutants.

Eat more You don't need to do much to enhance salmon's taste, says Sidra Forman, a chef and writer in Washington, D.C. "Simple is best. Season a fillet with salt and pepper, then cook it in a hot pan with 2 tsp oil for 1 to 3 minutes on each side."

Apples

An apple a day can keep weight gain at bay, finds a study from Penn State University at University Park. People who chomped an apple before a pasta meal ate fewer calories overall than those who had a different snack. "Apples are high in fiber—4 to 5 grams each—which makes them filling," says Susan Kraus, R.D., a clinical dietitian at Hackensack University Medical Center in New Jersey. Plus, the antioxidants in apples may help prevent metabolic syndrome, a condition marked by excess belly fat or an "apple shape."

Eat more Apples are the ideal on-the-go low-calorie snack. For a pielike treat, chop up a medium apple and sprinkle with 1/2 tsp allspice and 1/2 tsp cinnamon. Pop in the microwave for 1 1/2 minutes.

Buckwheat pasta

Swap plain noodles for this hearty variety; you'll slip into your skinny jeans in no time. "Buckwheat is high in fiber and, unlike most carbs, contains protein," Zuckerbrot says. "Those two nutrients make it very satiating, so it's harder to overeat buckwheat pasta than the regular stuff."

Eat more Cook this pasta as you do rice: Simmer it, covered, over low heat. For a light meal, toss cooked buckwheat pasta with broccoli, carrots, mushrooms and onions. Or make buckwheat crepes using our tasty recipe.

Blueberries

All berries are good for you, but those with a blue hue are among the best of the bunch. They have the highest antioxidant level of all commonly consumed fruit, according to research from the USDA Agriculture Research Service in Little Rock, Arkansas. They also deliver 3.6 grams of fiber per cup. "Fiber may actually prevent some of the fat you eat from being absorbed because fiber pulls fat through the digestive tract," Zuckerbrot says.

Eat more Instead of topping your cereal with fruit, fill your bowl with blueberries, then sprinkle cereal on top and add milk or yogurt, Iserloh recommends.

Almond butter

Adding this spread may lower bread's glycemic index (a measure of a food's effect on blood sugar). A study from the University of Toronto found that people who ate almonds with white bread didn't experience the same blood sugar surges as those who ate only the slice. "The higher blood sugar levels rise, the lower they fall; that dip leads to hunger, causing people to overeat," says study author Cyril Kendall, Ph.D. "Furthermore, blood sugar changes cause the body to make insulin, which can increase abdominal fat."

Eat more Try it for a change from peanut butter in sandwiches, or make a veggie dip: Mix 1 tbsp almond butter with 2 tbsp fat-free plain yogurt, Iserloh suggests. Or add a dollop to oatmeal for flavor and protein.

Pomegranates

The juice gets all the hype for being healthy, but pomegranate seeds deserve their own spotlight. In addition to being loaded with folate and disease-fighting antioxidants, they're low in calories and high in fiber, so they satisfy your sweet tooth without blowing your diet, Krieger says.

Eat more Pop the raw seeds on their own (many grocery stores sell them preshucked) as a snack at your desk. "Use them in salads instead of nuts," Iserloh says. "They're especially delicious on raw baby spinach with lemon–poppy seed dressing." For another take on the seeds, use our easy recipe for sweet and spicy pomegranate salsa.

Chiles

One reason to spice up your meals: You'll crank up your metabolism. "A compound in chiles called capsaicin has a thermogenic effect, meaning it causes the body to burn extra calories for 20 minutes after you eat the chiles," Zuckerbrot explains. Plus, "you can't gulp down spicy food," she adds. "Eating slowly gives your brain time to register that your stomach is full, so you won't overeat."

Eat more Stuff chiles with cooked quinoa and marinara sauce, then roast them. To mellow a chile's heat, grill it until it's almost black, peel off charred skin and puree the flesh, Krieger says. Add the puree to pasta sauces for a one-alarm kick. Or stir red pepper flakes into any dish you enjoy.

Yogurt

Dietitians often refer to plain yogurt as the perfect food, and for good reason: With its trifecta of carbs, protein and fat, it can stave off hunger by keeping blood sugar levels steady. In a study from the University of Tennessee at Knoxville, people on a low-calorie diet that included yogurt lost 61 percent more fat overall and 81 percent more belly fat than those on a similar plan but without yogurt.

Eat more "Use lowfat plain yogurt instead of mayonnaise in chicken or potato salad, or top a baked potato with a bit of yogurt and a squeeze of lemon juice," Krieger says. You'll save 4.7 grams of fat per tablespoon. Look for Greek yogurt, which has more protein than other versions.

Quinoa

Curbing hunger is as easy as piling your plate with this whole grain. It packs both fiber (2.6 grams per 1/2 cup) and protein, a stellar nutrient combo that can keep you satisfied for hours, Krieger says.

Eat more Serve quinoa instead of rice with stir-fries, or try Krieger's take on a scrumptious hot breakfast: Cook 1/2 cup quinoa in 2/3 cup water and 1/3 cup orange juice for 15 minutes. Top with 1 tbsp each of raisins and chopped walnuts.

Sardines

These tiny fish are the unsung stars of the sea. They are high in protein and loaded with omega-3s, which also help the body maintain muscle. And they're low in mercury and high in calcium, making them a smart fish pick for pregnant women. If the flavor doesn't appeal to you, "soak them in milk for an hour; it will remove any trace of fishiness," Iserloh says.

Eat more "Use sardines in recipes you like that call for anchovies, including Caesar salad and stuffing," Iserloh says. Or make a sardine melt: Toss whole sardines with chopped onions, fresh herbs and diced bell peppers. Put the mixture on top of a slice of pumpernickel or rye bread, cover with a slice of cheddar and broil.

Tarragon

You can use this herb, a staple in French cooking, in place of salt in marinades and salad dressings. Excess sodium causes your body to retain water, so using less salt can keep bloating at bay. Plus, tarragon lends a sweet, licoricelike flavor to bland foods. (Use the French version of the herb when possible; it's sweeter than other varieties.)

Eat more Rub 2 tbsp dried tarragon on chicken before baking or grilling. Or make a tasty dip by mixing 1 tsp chopped fresh tarragon into 4 oz lowfat plain yogurt and 1 tsp Dijon mustard, recommends Jacquelyn Buchanan, director of culinary development at Laura Chenel's Chèvre, a fromagerie in Sonoma, California.

Parmesan

Drop that rubbery lowfat cheese and pick up the real stuff. Women who had one serving of whole milk or cheese daily were less likely to gain weight over time, a study in The American Journal of Clinical Nutrition finds. Lowfat-dairy fans didn't experience the same benefit. Whole dairy may have more conjugated linoleic acid, which might help your body burn fat. "Parmesan is so flavorful, it's easy to stick to one serving," Buchanan says.

Eat more "Grate Parmesan over roasted vegetables," Buchanan offers. Or snack on a 1-ounce portion with an apple or a pear.

Avocado

Don't let the fat content of an avocado (29 grams) scare you—that's what makes it a top weight loss food, Kraus says. "The heart-healthy monounsaturated fat it contains increases satiety," she says. And it's terrific summer party food.

Eat more Add avocado to your sandwich instead of mayo for a creamy texture and a shot of flavor. Avocados do contain a lot of calories, so it's best to watch your portions. One easy way to do it: Try Wholly Guacamole's 100-calorie fresh guacamole packs ($3; grocery stores or WhollyGuac.com). They're easy to pack in your lunch and pair with chopped vegetables.

Olive oil

Like avocados, olive oil has healthy fat that increases satiety, taming your appetite. But that's hardly its only slimming feature. "Research shows it has anti-inflammatory properties," Kraus says. Chronic inflammation in the body is linked to metabolic syndrome.

Eat more Drizzle your salad with olive oil and you'll increase the antioxidant power of your veggies, a study published in the British Journal of Nutrition notes. Or toss pasta with a few teaspoons of olive oil, fresh basil and sautéed garlic, Kraus suggests. Add this oil to your summer menus for a flatter tummy by fall.