WHY YOU NEED THEM Carbs, found in fruit, vegetables and grains, are the primary source of fuel for your body; they should supply about half of the calories in your daily diet. Carbohydrates contain 4 calories per gram and are digested quickly.
DIET FRIEND OR FOE? Friend, as long as you stick to the healthy ones. What separates a good carb from a bad carb is its nutritional makeup: Good carbohydrates, like whole grains and produce, contain vitamins, minerals and fiber, which slows digestion and keeps you feeling full longer. On the other hand, bad carbs such as cookies and white bread usually provide no other nutrients and can rev your appetite: When you eat a bad carb alone, your body digests it so quickly that you get a surge followed by a dip in blood sugar. This can leave you hungry soon after and may eventually lead to weight gain and an increased risk for diabetes.
BEST PICKS Fruit, legumes, lowfat milk, nonfat yogurt, vegetables, whole grains (brown and wild rice, bulgur, corn, oatmeal, quinoa), whole-wheat bread or pasta (look for 100 percent whole wheat on the label)
CUT BACK ON Bagels, cake, candy, cookies, fruit juice, honey, muffins, potato chips, pretzels, regular pasta, soda, sweetened tea, table sugar (brown or white), white bread, white rice.
TOP CARB MYTH Carbs make you fat. “Calories that come from carbohydrates—good or bad—are stored as fat only if you eat more than your body needs,” says Cynthia Sass, R.D., coauthor of Your Diet Is Driving Me Crazy (Marlowe). There is, however, a grain of truth in the myth: Most of us eat more carbs than we require. A report from the Centers for Disease Control and Prevention in Atlanta shows that women today eat about 300 calories more per day than women did in the 1970s—mostly from carbs. But cutting them out completely isn’t the solution, Sass says. Instead, focus on choosing the right kind: The intake of processed carbs is associated with a higher body weight, but the intake of total carbs is not, a study in the American Journal of Epidemiology shows. So go for the good carbs, and eat an amount that fits your activity level. If you’re a moderately active 33-year-old woman, you can have a serving or two of grains at breakfast, lunch and dinner. And limit sweet snacks to 250 calories. Love pasta and potato chips? Exercise more.
FASCINATING CARB FACT The USDA used to lump all types of grains together, but in the latest version of the food pyramid, released in April, the agency separated the good carbs from the bad. The new recommendation advises you to get a minimum of half of your six daily grain servings from whole-grain sources, like brown rice and oatmeal. And with good reason: The fiber in whole grains not only helps with weight control, but it also keeps your digestive system and heart healthy and may protect against diabetes. (Fruit and veggies are their own distinct categories in the food pyramid, and you should aim for a daily total of at least 4 cups.)
WHY YOU NEED IT Fat has more than twice as many calories—per gram—as carbs or protein, but it’s essential: Eating fat helps the body absorb disease-fighting phytochemicals and fat-soluble vitamins. Plus, it’s filling because it takes longer than carbs or protein to leave the stomach. There are four types of fat: saturated, monounsaturated, polyunsaturated (which includes omega-3 and omega-6 fatty acids) and trans fat. Roughly a third of your total daily calories should come from fat—ideally the healthy kinds.
DIET FRIEND OR FOE? The good fats, which include monounsaturated (in olives and nuts) and polyunsaturated (in fish and many oils), lower “bad” LDL and increase “good” HDL cholesterol. But the saturated fat in meats and full-fat dairy increase LDL. Trans fats, unsaturated fats that have been partially hydrogenated by manufacturers to extend a product’s shelf life, may be even worse because they lower good cholesterol in addition to raising the bad. Having trouble telling good fats from bad? Here’s a hint (it only works with sources that are purely fat, but hey, it helps): Saturated fats are solid at room temperature (butter, lard, margarine); unsaturated fats are liquid (oils).
BEST PICKS Monounsaturated fats: avocado, canola and olive oils, and nuts. Polyunsaturated fats: corn and soy oils, flax (seed and oil), herring, sardines, walnuts and salmon
CUT BACK ON Fatty meats, full-fat dairy, products with trans fat (Look for partially hydrogenated in the ingredients list. As of 2006, labels must include the amount of trans fat.)
TOP FAT MYTH You need to avoid fats to be healthy. A study from the International Journal of Obesity found that people on a low-calorie diet consisting of 35 percent fat lost an average of 9 pounds over 18 months, while those on a lower-fat diet (20 percent) gained 6 pounds. Why? Only 20 percent of the lowfat dieters were able to stick to the plan, versus 54 percent of those on the higher-fat plan. “Fat can provide up to 35 percent of our total calories as long as it comes from sources that are low in saturated and trans fats,” Sass says. “A lowfat meal is not better for you than a higher-fat meal, but a meal that replaces animal fat with plant fat is.” If you’re active, your diet can be a little higher in fat because exercising puts extra stress on the body, and fat helps in the healing process. Still, because fat has more than twice the calories of carbs and protein, choose wisely. “Eat more unsaturated fats, such as those in salmon and olive oil,” says Lisa Young, Ph.D., author of The Portion Teller (Morgan Road Books).
FASCINATING FAT FACT Eating the right balance of fats has another perk: It can help fight inflammation, which has been shown to be a factor in heart disease, Alzheimer’s disease and cancer. Inflammation is the body’s response to injury. You see it whenever you cut yourself: The skin turns red and swells as blood rushes to the area. When this response is quick and confined, the result is positive—you heal. But long-lasting inflammation may lead to chronic disease, preliminary research reveals.
Scientists don’t know all of the factors that stimulate this uncontrolled systemic inflammation, but smoking, stress, a sedentary lifestyle and untreated infection have all been identified as contributors. So, too, has a diet low in omega-3 fatty acids, which are found in fish and flax. (Omega-6 fatty acids, in foods like olive and canola oil, are ubiquitous, so you get enough without even trying.) “Omega-6 fats promote inflammation, and omega-3 fats hinder it,” says Lona Sandon, R.D., of Dallas, a spokeswoman for the American Dietetic Association. But omega-6 fats aid the healing process as long as they’re balanced with omega-3s. To keep your omega fatty acid levels in check, go for more omega-3 fats. And cut the junk. A study in The American Journal of Clinical Nutrition revealed that trans fats were associated with greater inflammation among healthy women.
WHY YOU NEED IT Foods rich in protein provide the nine essential amino acids your body requires to repair itself and to make the enzymes, immunological cells, hormones and neurotransmitters you need to live. Protein should account for about 20 percent of your daily calories.
DIET FRIEND OR FOE? Lean proteins such as poultry, egg whites and fish are your pals, containing minimal amounts of heart-harming saturated fat. They also blunt hunger and keep blood sugar stable. The not-so-trim ones, such as certain cuts of red meat (ribs, T-bone steak or ground beef that’s less than 80 percent lean), are significant sources of saturated fat.
BEST PICKS Egg whites, fish, lean pork, lean red meat, legumes, lowfat dairy, nuts, shellfish, skinless poultry, soy
CUT BACK ON Fatty meat, full-fat dairy, high-protein energy bars (which are often very high in calories)
TOP PROTEIN MYTH Eating protein increases lean muscle mass and revs metabolism. “Protein helps you maintain muscle mass,” Sass says. “But you’ll only increase muscle mass if you are strength training, because the nutrient helps repair the tiny muscle tears that occur. As your muscles rebuild, they become stronger.” As for whether protein boosts metabolism, though there’s some evidence that digesting burns more calories, it’s not enough to make a noticeable difference, Young says.
FASCINATING PROTEIN FACT The Atkins diet works not because you’re avoiding carbs, but because you’re eating more protein. In fact, a study in The American Journal of Clinical Nutrition shows that adding protein while also cutting back on fat instead of carbs caused dieters to spontaneously reduce their overall calorie intake by an average of 441 calories a day. Protein is more satiating than carbs or fat, and experts suggest that’s because it enhances the effect of leptin, a hormone that helps the body register fullness. Master the nutrient balancing act— 50 percent of calories from carbs, 30 percent from fat, 20 percent from protein—and watch the pounds peel off.