Fat and WeightEven as Americans have been gaining weight, they have cut their average fat intake（摄入） from 36 to 34 percent of their total diets in the past 15 years. Fat has nine calories per gram. Protein and carbohydrates（碳水化合物）have just four. Moreover, the body uses fewer calories to metabolize（代谢）fat than it does to metabolize other foods.Compared with protein and carbohydrates, fat is more easily changed to body fat. Therefore, it's more likely to store on buttocks（臀部）,thighs and bellies.But cutting fat from your diet doesn11 necessarily mean your body won't store fat. For example, between nonfat and regular cookies, there' s little difference in calories because producers make up for the loss of fat by adding sugar. Low-fat crackers, soups and dressings（调料）can also be just as high in calories as richer versions. No matter where the calories come from, overeating will still cause weight again. The calories from fat just do it a little quicker. A Wisconsin computer programmer decided to eat only 40 grams of fat a day. And later he found that he wasn't losing weight. Then he showed his food diary to a doctor and said he'd been eating half a pound of jelly beans a day."They don' t have any fat，"he explains. But they had enough sugar to stop him from losing an ounce of his weight.Nonfat foods become add-on foods. When we add them to our diet, we actually increase the number of calories we eat every day and gain weight. For breakfast, Prof. Rolls gave two groups of women yogurt that contained exactly the same amount of calories. One group' s yogurt is with “ high fat" label—the other, "low fat". The "low fat" yogurt group ate more calories later in the day than the other group. " People think they've saved fat and can indulge themselves later in the day with no harmful results, says Richard mattes, a nutrition researcher at Purdue University. M But when they do that, they often end up overdoing it."1.Americans' average fat intake decreased by 2 percent in the last 15 years.
笔果题库
