Myth 1: Potatoes and bread are fattening.
Actually: It's just the opposite. Starchy vegetables and bread (whole-grain bread, that is) are quality carbs needed to fuel every part of you, from your brain to your muscles. Where you can get into trouble is how you eat them: Smear butter on a slice of whole wheat bread or deep-fry potatoes and you can double, triple, or quadruple their calories.
Myth 2: Drinking a glass of water before a meal curbs appetite.
Actually: Yes and no. Water tames appetite if it's incorporated into food, such as soup or a thick drink (think V8 juice). Apparently, when water is bound to food, digestion is slower, explains Elizabeth Somer, RD, author of 10 Habits That Mess Up a Woman's Diet. That's why in one study women found chicken-rice soup more satisfying than chicken-rice casserole and a glass of water--even though the soup had 27% fewer calories! One exception to this rule: Because it's easy to confuse hunger and thirst, if you find yourself craving something--but what?--drink a big glass of water and wait a few minutes. You may find that's what you really wanted.
Myth 3: Shellfish is high in cholesterol.
Actually: On one hand it's true, just three ounces of shrimp deliver more than a third of your daily cholesterol, but there's a surprising flip side to this story: Shrimp are low in saturated fat--the kind that becomes artery-clogging bad cholesterol--and they have a smidgeon of heart-healthy omega-3s. In fact, University of Southern California researchers discovered eating shellfish, such as shrimp, every week reduced heart attack risk by 59%!
Myth 4: The occasional burger and fries won't kill you.
Actually: If "occasional" means every Friday night, then no. But if it means every few months, and you're fit, and you've got good "numbers" (weight, waist size, cholesterol, blood pressure) AND you're chowing down on vegetables, whole grains, nuts, and other nutritious fare most other days, hey, you'll live. But few of us are that perfect. If you do occasionally indulge? Offset the effects of a fat fiesta with a brisk, 90-minute walk afterward.
Myth 5: Women naturally gain weight after menopause.
Actually: While you can blame a lot of things on hormones (from acne to PMS), in this case slowing down physically is far more likely at fault. Study after study has found that older women who exercise regularly and vigorously maintain their girlish figures. What about those charts that say as you get older, you need to eat fewer calories to simply maintain your weight? Same story. The research doesn't show that age (instead of inactivity) accounts for the drop.
Myth 6: Diet soda is better than the real thing.
Actually: Soft drinks now outrank coffee as America's favorite beverage, but we all would be better off switching to water, diluted juice, and green tea than drinking either diet or regular soda. Both increase kidney and heart disease risk, plus they contain acids that erode tooth enamel, inviting cavities.