If your quest for washboard abs has you crunching like crazy, listen up: “There’s no single exercise move—or magic pill, for that matter—that instantly zaps belly fat,” says Sari Greaves, R.D., a New York City nutritionist. “You have to lose overall body fat to trim your midsection.” But what you put on your plate can determine how easily you lose those pounds: Scientists at Boston University found that women who followed a lowfat diet rich in fiber and other nutrients were three times less likely to pack on weight around the middle than those who ate less-healthy fare but 400 fewer calories. Here, we show you which flab-fighting foods to add to your shopping list—and which to blacklist.

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Melon At fewer than 50 calories a slice, this is one sweet treat you can feel free to indulge in. “Both honeydew and cantaloupe are high in potassium,” says Greaves. “This mineral keeps sodium levels in check and beats belly bloat.”

Wine A study in the Journal of Clinical Endocrinology & Metabolism found that people who averaged a serving of alcohol a day had slimmer waistlines than their teetotaling counterparts. “Drinking a small amount of alcohol with a meal may speed up calorie burn,” says Jerry Greenfield, M.D., Ph.D., the study’s author.

Whole-grain bread Researchers at Penn State found that dieters who ate at least five servings of whole grains while following a low-calorie diet shed 24 percent more abdominal fat than those who averaged the same number of calories but ate refined grains. To up your intake, swap your cornflakes for oatmeal.

Grapefruit Add zing to your snacks with this vitamin C–rich fruit. Research in Public Health Nutrition found that people who consumed the least amount of this nutrient were 131 percent more likely to have larger waists than those who got the most. Other studies suggest that grapefruit can curb the insulin spikes that lead to fat storage.

Walnuts Research shows that their omega-3 fatty acids lower levels of stress hormones, such as cortisol, that can contribute to fat storage. To get more omega-3s, sprinkle some ground flaxseed on your yogurt.

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Sugar substitutes Although they curb calories, those pink, blue, and yellow packets can make your stomach swell. “Some people have difficulty digesting artificial sweeteners, such as sorbitol and xylitol,” says Greaves. “That can cause bloating and diarrhea.” Try weaning yourself off them by using a small amount of real sugar. (One teaspoon has 16 calories.)

Canned soup Many boxed, canned, and frozen processed foods are stealthy sources of sodium. A cup of chicken noodle, for instance, can pack in more than a third of your 2,400-milligram daily limit. “Even a small amount of excess sodium can cause your body to retain water,” says Greaves, who recommends choosing low-sodium soups.

Partially hydrogenated oil Researchers from Wake Forest University found that eating a diet high in trans fats may actually cause fat in the body to redistribute itself to the belly. Because “trans fat– free” foods can contain up to 0.5 grams of the stuff per serving, scan ingredient lists on packages.