Myth No. 1: Don't Eat After 8 p.m.

RealSimple: Busting 10 Diet Myths

The honest-to-goodness truth about how to keep your weight under control.

The theory: You burn up the food you eat earlier in the day, while late-night calories sit in your system and turn into fat.

The reality: Calories can't tell time. "Your body digests and uses calories the same way morning, noon, and night," says Mary Flynn, Ph.D., a research dietitian at the Miriam Hospital, in Providence. They may

sit around a little longer if you eat, then lie on the couch and watch Letterman, but when you move around the next day, your body will dip into its stores. That said, there are other solid reasons to avoid late-night snacking, not least of which is that snacks you grab when you're tired tend to be unhealthy ones.

The best advice: If you often unwind before bed with a bowl of ice cream or buttered popcorn, try cutting the snack out. The calories saved may be enough for you to lose a few pounds a year. If you're hungry, "eat something on the light side, like a piece of fruit or some cereal with milk," says Ellie Krieger, a registered dietitian and the author of "The Food You Crave" ($28, amazon.com). Night eaters tend to overeat (which leads to weight gain no matter when it's done) because often they've been skimping during the day and come home famished. Being so hungry that you grab whatever is at hand means you're more likely to make poor choices. "Don't go longer than about five hours without eating," says Jo Ann Hattner, a registered dietitian and a nutrition consultant in San Francisco. Just be careful to keep your meals and snacks small.

(Cig Harvey)

The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.

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Myth No. 1: Don'...

Myth No. 2: Eati...

The theory: If you keep adding small amounts of food to your fire (the fire being your metabolism), you will keep it going strong and burn more calories overall.

The reality: Food intake has a negligible effect on metabolism. Some foods, including those with caffeine, may slightly and temporarily increase metabolism, but the effect is too small to help you lose weight. What most affects your basal metabolic rate (BMR), the rate at which your body burns calories at rest, is body composition and size. More muscles and bigger bodies generally burn more calories overall.

The best advice: Build up your muscles. A pound of fat-free tissue burns about 14 calories a day, while a pound of fat burns just two to three calories. And while that difference may not sound like a lot, it will certainly help over time. Remember, too, that when you lose pounds, part of that weight is muscle, warns Liz Neporent, an exercise physiologist and the president of Wellness 360, a New York City-based corporate-wellness-consulting company. That's why strength training is even more important if you're on a weight-loss mission. Try lifting weights, or you can maintain your muscles by going to a Pilates, body-sculpting, or power-yoga class two to three times a week.

(Anna Williams)

The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.

Myth No. 3: Past...

The theory: When you eat carbohydrates, your body turns them into sugars, which are then stored as fat.

The reality: Carbohydrates per se don't make you fat; extra calories do, whether you eat them in the form of carbs, fats, or protein. Besides, carbohydrates include vegetables, fruits, and whole grains, which are important parts of a healthy diet. In short, the problem isn't pasta but the sheer volume consumed. "Americans tend to eat

too much carbohydrates, fat, and protein. But they overeat carbs most of all," says Barbara Moore, Ph.D., a nutritionist in Clyde Park, Montana, and a spokesperson for the American Society for Nutrition. "You go to a restaurant and you're served three cups of pasta with lots of sauce." Those three cups of pasta can pack up to 600 calories without the sauce.

The best advice: Pasta in moderation is fine. Dietitians recommend two or three ounces of uncooked noodles per person?or half of a one-pound box to serve a family of four. This may look like a puny amount, but try thinking of "pasta as an ingredient, rather than as the basis of a dish," says Mark Bittman, author of "How to Cook Everything Vegetarian" ($35, amazon.com). "Start with a lot of grilled or sautéed vegetables and maybe a tomato-based sauce. Then add some pasta, sparingly." If you want protein, add beans, chicken or shellfish. (For some delicious pasta dishes, see 6 Healthy Pasta Recipes). Make your pasta?or bread or rice or cereal?whole-grain, which has more vitamins and minerals than white pasta. You'll also be getting fiber, which helps you feel full.

(Sang An)

The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.

Myth No. 4: Coff...

The theory: The caffeine in coffee acts as an appetite suppressant and a metabolism booster.

The reality: While coffee may temporarily squelch your appetite, drinking a couple of cups a day won't have enough of an effect to help you lose weight. Besides, pouring too much coffee into your system?drinking, say, four to seven cups a day?may lead to anxiety, sleeplessness, and an increase in heart rate and blood pressure.

The best advice: Enjoy a cup or two of coffee (or tea) every day, if you please. Just be sure that if you add anything to the brew?like cream, sugar, or cocoa powder?you take those calories into account. For example, a 16-ounce Starbucks Café Mocha can contain a whopping 330 calories (60 more than some chocolate bars). What's more, those calories might not make you feel as full as the same number of calories eaten in solid form. Another coffee concern: sleep disruption, which new evidence reveals is linked to weight control. "Every time people feel tired, they think, I have to have a latte," says Liz Applegate, Ph.D., director of sports nutrition at the University of California, Davis. "They become addicted to caffeine on a higher level, and it takes four to six hours to clear out of the system. Sleep is not as good, and you're tired the next day." And probably hungrier, too. At least two studies have shown that when people are sleep-deprived, they produce more of the hormone ghrelin, an appetite stimulant, and less leptin, an appetite suppressant. Not to mention that your resistance to the doughnut's siren song is a whole lot lower when you're pooped.

(Beatriz da Costa)

The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.

Myth No. 5: Milk...

The theory: Calcium helps the body break down fat more efficiently, stimulating weight loss.

The reality: Dairy doesn't appear to have magic properties. A few studies from the mid-2000s concluded that dieters who consumed dairy lost more weight than dieters who did not. But other studies showed no effect, and still others showed a link between high milk consumption and eating more calories.

The best advice: Go ahead and eat dairy products, but stick with low-fat versions, which are lower in both calories and unhealthy saturated fats. Milk products are loaded with calcium, of course, but how much calcium you need is a matter of debate. The government recommends at least 1,000 milligrams of calcium for adults under 50 years old (about the amount in three cups of milk) and 1,200 milligrams for people over 50; however, the Harvard School of Public Health holds that no one really knows the healthiest, safest amount of calcium that adults should consume. If dairy products don't agree with you, you can get calcium from fortified soy milk; fortified orange juice; dark green, leafy vegetables, such as kale and collard greens; and certain fish, such as canned salmon.

(Beatriz da Costa)

The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.

Myth No. 6: Goin...

The theory: Switching to a prescriptive plan temporarily is the smartest way to drop pounds.

The reality: Short-term, you do lose weight on any plan that results in your eating fewer calories. But temporary changes don't lead to permanent losses. "A diet won't work if you think of it as doing a different thing for a while and then you're going to stop doing it," says Christopher Gardner, an assistant professor of nutritional science at Stanford University School of Medicine. "If you have a new way of eating and think, I'm going to eat like this forever, that's the way to lose weight." And keep it off.

The best advice: Don't go on a "diet"?a quick fix that begins on New Year's Day or before bathing-suit season. Instead, change the way you eat. Find a satisfying eating plan that you can live with long-term, and make sure you're eating the right amount of calories for weight loss. Then, when you've taken off some weight, don't go back to eating as much as you did before you cut calories. "To maintain a lighter weight, you have to eat a little less than you did to maintain your heavier weight before," says Gardner. Besides, dieting alone won't work as well as dieting plus exercise?a little bit of exercise, or maybe a lot. Since 1994 the National Weight Control Registry has followed and analyzed the habits of successful weight losers (defined as people who have maintained at least a 30-pound weight loss for a year or more). Among its findings: Those who kept weight off exercised?with brisk walking or some other moderate-intensity activity?an average of one hour a day. "One of the most important aspects of weight maintenance is a high dose of physical activity," says Rena Wing, Ph.D., a cofounder of the registry and a professor of psychiatry and human behavior at the Warren Alpert Medical School, at Brown University.

(Beatriz da Costa)

The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.

Myth No. 7: Eati...

The theory: Protein and carbohydrates require different enzymes for digestion; if you eat the two separately, you improve digestion and further weight loss.

The reality: Your digestive tract can handle a variety of food groups at the same time. There is no proof that eating protein and carbohydrates separately aids digestion or weight loss, says nutritionist Christopher Gardner. Indeed, it's healthier to combine protein and fiber-filled carbs than to

separate them. "The pairing of protein and fiber is what fills you up the most and gives you the most energy," says Elisa Zied, a New York City-based registered dietitian and a spokesperson for the American Dietetic Association. "An apple is good, but an apple with peanut butter is more filling." Also, some of the best foods for you?nuts, seeds, legumes?are made up of both protein and carbohydrates. "To people who say that you should separate protein and carbohydrates, I say, 'Why did God make beans?'" says dietitian Ellie Krieger.

The best advice: Eat protein along with carbs, but choose with care. The best protein choices are lean meats, poultry, low-fat dairy products, and tofu, because they have little (if any) saturated fat. The best carbs are whole grains, fruits, and vegetables, which offer more health benefits than refined grains. "Those foods take longer to absorb, so there's a slower release into the body and a more steady energy source," says Hope Barkoukis, an assistant professor of nutrition at Case Western Reserve University, in Cleveland.

(Beatriz da Costa)

The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.

Myth No. 8: To L...

The theory: Eat much less; weigh much less.

The reality: Sure, if you subsist on 1,200 calories a day, you'll take off weight, but it won't be for long. Consider an analysis of 31 studies of long-term diets, where the diets averaged 1,200 calories a day. The report, published last April in American Psychologist, found that within four to five years, the majority of dieters in these studies regained the weight they had lost.

"Psychologically, it's difficult for people to adhere to strict diets over a long period because they feel deprived and hungry," says Traci Mann, an associate professor of psychology at the University of Minnesota, in Minneapolis, and the lead author of the report. "Also, our bodies are brilliant at keeping us alive when we try to starve them." Your body becomes more efficient at using the calories you consume, so you need fewer to survive. In addition, people who are put on a very-low-calorie diet (800 calories a day) have an increased risk of developing gallstones and digestive issues.

The best advice: Don't starve yourself. "If you want to lose weight and keep it off forever, you need a modest calorie restriction that you simply continue and never stop," says nutritionist Christopher Gardner. But what's the right number of calories for you? Use this easy formula, a favorite of cardiologist Thomas Lee, editor in chief of the Harvard Heart Letter.

First, find your activity level below (“And Your Number Is...”). Multiply your weight by the number indicated. (You may fall between two categories. If that's the case, adjust the number by adding a point or so.) The result is the number of calories you need to maintain your weight. Let's say you weigh 135 pounds and do light exercise one to three days a week. Multiply 135 by 13.5 to get, approximately, 1,800 calories. If you want to drop some pounds, try cutting out 250 calories a day, says Lee. In a year, if you make no other changes, you could be 26 pounds lighter. Exercise more and you could lose more, too.

And Your Number Is…

You exercise: Almost never
Multiply your current weight by: 12

You exercise: Lightly, one to three days a week
Multiply your current weight by: 13.5

You exercise: Moderately, three to five days a week
Multiply your current weight by: 15.5

You exercise: Vigorously, six to seven days a week
Multiply your current weight by: 17

You exercise: Vigorously, daily, and you have a physical job
Multiply your current weight by: 19

(Kana Okada)

The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.

Myth No. 9: Diet...

The theory: Low-fat, low-carb, and artificially sweetened packaged foods make losing weight painless.

The reality: Low-fat and low-carb don't always mean low-cal, and if you're trying to lose weight, stocking up on these treats could undermine your efforts. In a series of recent studies, for instance, participants ate up to 50 percent more of foods that the researchers falsely labeled "low-fat" than they did of the same exact foods with real

labels. "Consumers expect that low-fat M and M's contain 20 percent fewer calories than their regular counterparts," concluded the authors of the studies, Brian Wansink, Ph.D., and Pierre Chandon, Ph.D., in the Journal of Marketing Research, in November 2006. "Importantly, as a result, they expect that comparable increases in serving sizes are justified." Some experts also believe that consuming artificial sweeteners might backfire. Two long-term studies looking at the drinking habits of thousands of people have found a correlation between drinking diet soda and being overweight.

The best advice: When you're tempted by a snack food that's labeled "light" or "low-fat," check the nutrition label. Look at how many calories are in a serving, then compare that number with the calories in a comparable product that's not making a label claim. And then consider having just a small amount of the real thing. You may end up consuming fewer calories with, say, a full-fat product than you would with a low-fat version, because fat tends to be more satisfying. And take care that you don't decide?consciously or not?that substituting a diet soda for a full-sugar one gives you license to eat a box of Valentine's chocolates instead.

(Quentin Bacon)

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Myth No. 10: Eat...

The theory: Fat has nine calories per gram, whereas carbs and protein have only four per gram, so to lose weight you have to avoid fat.

The reality: Fat is not the enemy. Although fat-laden products can be full of calories, a modest amount of fat may help you feel full (so you eat less overall) and make healthy foods, like vegetables, taste better (so you may eat more of them). Fat also helps with the absorption of certain vitamins and phytonutrients, which are compounds in plants that are thought to promote health.

The best advice: Eat fat, but don't go overboard. And think about which fats you do eat, as some are better for you than others. Choose monounsaturated and polyunsaturated fats, found in liquid oils such as canola, safflower, and olive; most nuts; and fish. These fats don't raise blood cholesterol levels and may reduce your risk of cardiovascular disease. The fats to limit or avoid are saturated fats, found mainly in beef and dairy products, and trans fats, which are in a lot of packaged foods, fried fast foods, and margarine. These are no more caloric than the good fats, but they are less healthful, as they increase the risk of heart disease. The Institute of Medicine, which advises the government on scientific matters, including health, recommends that when it comes to saturated fat, cholesterol, and trans fats, you eat as little as possible. If we've learned anything as we've swung from low-fat to low-carb and back again, it's this: There's no need to eat dry salad or forgo any food you adore. Most everything in moderation will keep your weight where it belongs.

(Beatriz da Costa)

The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.