If you have gone on a diet and reached your goal, chances are good that when

游客2024-06-09  10

问题     If you have gone on a diet and reached your goal, chances are good that when you stop dieting you will regain all the weight you lose. After several weeks on a low-calorie diet—900 calories or fewer— the body conserves energy by showing the speed at which it burns calories. This slow-down explains in part why your weight loss may cease after a few weeks. When you eventually return to eat a normal amount of food, your body may continue to burn calories at the slower rate, storing the remaining calories as fat. So if you are on a strict diet, your body may need fewer calories to maintain the same weight; losing weight becomes more difficult.
    Doctors know that as you gain weight the fat cells in your body (most of us average 30 billion of them) become enlarged. But there is a limit to how big a fat cell can get, and very fat people develop additional fat cells—something more than 100 billion. It now appears that you can add fat cells at any point during your life, although the number you have is influenced by a combination of your history of dieting and your genetic makeup.
    Fat cells differ distinctly from other cells in that they are made mostly of fat instead of protein and apparently they never go away, even after dieting. Instead, they merely shrink. Dr. Jukes Hirsch of Rckefeller University has examined the body tissue of very fat people who have lost weight, and found that it resembles that of starvation victims. Perhaps, he supposes, it is the billions of undersize, "hungry" cells that drive many formerly fat people off their diets.
    New research reveals that your hungry cells aren’t the only signal senders that tempt you toward the refrigerator. Another culprit may be the hormone insulin. Insulin tums sugar and fat into fuel for the body. In addition, some researchers believe that high levels of insulin are a factor in hunger and appetite—and may drive you to overeat.
    Exercise helps maintain your weight and seems to bring insulin levels down, says Dr. Donald S. Robertson, a medical director. "Any weight -loss program must fail," he said, "unless it incorporates a certain amount of exercise." [br] The best title for the passage may be______.

选项 A、Dieting Is No Way to Lose Weight
B、The Best Method of Losing Your Weight
C、Causes of Gaining Weight
D、Recent Researches on Overweight

答案 A

解析 主旨大意题。第一段讲到由于身体自身机能,节食减肥到了一定程度就很难有所发展了;接下来三段具体讲了体内脂肪细胞的工作原理使得减肥失败,除此之外,荷尔蒙胰岛素也使人难耐饥饿;最后一段讲到,节食与体育锻炼需结合进行。综合全文来看,文章主要讲了节食并非减肥良方,因此A项为最佳答案。主旨题考查的是对文章中心的理解,一篇文章看{以讨论了很多内容,其实只围绕一个中心议题展开,主旨题一般不会是段落中的小议题。文章始终在说节食减肥方法的弊端,没有提到减肥的最佳方法,因此排除B;C“肥胖的原因”,文章有解释节食减肥后肥胖的原
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