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  3. Getting Thin—for Good A)Just about everyone has been on a diet at one time or another, and millions of us have learned that the

Getting Thin—for Good A)Just about everyone has been on a diet at one time or another, and millions of us have learned that the

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问题                         Getting Thin—for Good
A)Just about everyone has been on a diet at one time or another, and millions of us have learned that the weight we lose is all too easily regained. Still few people question the wisdom of dieting. After all, we reason, the worst that can happen is that we’ll regain the weight we’ ve lost—then we can simply go on a diet again.
B)But some new research suggests there is a risk: yo-yo dieting may seriously distort the body’s weight-control system. The more diets you go on, the harder it may become to lose weight. Even worse, new evidence indicates that repeated cycles of losing and gaining weight may raise the risk of heart problems.
C)This last possibility is especially disturbing. As part of a 25-year study that monitored 1,959 men, researchers at the University of Texas School of Public Health in Houston reported in March 1987 that the men showing large up-and-down weight changes had twice the risk of heart disease as those with only small changes in weight. One paper from the Framingham(Mass.)Heart Study, which has monitored more than 5,000 people for 40 years, also provides troubling information: people who lost ten percent of their body weight had about 20 percent reduction in risk of heart disease—but people who gained 10 percent raised the risk by 30 percent. These numbers further suggest that going from 150 to 135 pounds, and back to 150 again, could leave you with a higher heart-disease risk than you started with.
D)When you cut calories and lose weight, your body will protect itself by reducing your basal metabolic rate(BMR). This is the measure of the energy used for routine functions such as breathing and cell repair—roughly 60 to 75 percent of the energy consumed by the body. During severe dieting, your BMR drops within 24 hours and can decline a full 20 percent within two weeks. This metabolic decline is one reason dieters often reach a steady unchanging period, and find that the same caloric intake which melted pounds earlier now produces no weight loss.
E)The body adapts to dieting in other ways. The enzyme lipoprotein lipase(脂肪酶), a chemical in the body, which controls how much fat is stored in fat cell, may become more active in some overweight people after they have lost weight. That would make the body more efficient at fat storage—exactly what the dieter doesn’t want. And this change, like the drop in BMR, may be part of the reason dieters frequently regain their lost weight.
F)My interest in the yo-yo problem began in 1982, when my colleagues Thomas Wadden and Albert Stunkard and I were experimenting with very-low-calorie diets—800 calories or fewer per day. We hoped that patients in our clinic could lose large amounts of weight rapidly, then keep the weight loss with a behavior-modification program.
G)We found, however, that some people lost weight rapidly, some slowly; some lost for a while and then stopped losing. One woman, Marie, began the program at 230 pounds, reduced to 192 pounds, and then "hit a wall", even though she stayed on her diet and walked two miles a day. Marie, like many others in our program, had been a yo-yo dieter, and they tended to have the most difficulty in losing weight.
H)To see if such dieting could really change the body this way, other researchers and I began to study weight changes in animals. We fed a group of rats a high-fat diet until they became obese. Then we changed their diets repeatedly to make them lose weight, regain, lose again and regain again.
I)The results were surprising. The first time the rats lost weight, it took 21 days for them to go from obese to normal weight. On their second diet, it took 46 days, even though the rats consumed exactly as many calories.
J)With each yo-yo, it became easier for the rats to regain. After the first diet, they took 46 days to become obese again; after the second diet, they took only 14 days. In other words on the second yo-yo cycle, it took more than twice as long to lose weight, and only one-third as long to regain it.
K)Surprised, our group contacted Harvard surgeon George Blackburn, a pioneer in the use of very-low-calorie diets. Blackburn and his colleagues reviewed the records of 140 dieters who had been through their weight-control clinic, had lost weight and regained it—and had returned for a second try. The records showed the dieters had lost an average of 2.3 pounds a week the first time, but only 1.3 pounds a week the second time.
L)Four years ago we began the Weight Cycling Project, a major study that includes some of the country’ s leading obesity researchers. We know that people who lose weight by dieting only and without an exercise program can lose a considerable amount of muscle. But then, if they gain weight back, they may regain less muscle and more fat. While the reason isn’t clear, it may be easier for the body to put fat on than to rebuild lost muscle. We’re asking if yo-yo dieters may lose fat from one part of the body and regain it elsewhere. For instance, according to our preparatory studies in animals, they could move fat to the abdomen. And research shows that abdominal fat raises the risk of heart disease and diabetes more than fat around the hips and thighs does.
M)None of this means that dieting is ineffective or foolish. For those who are 20 percent or more overweight, there are good reasons to reduce: successful weight loss can lower blood pressure and cholesterol, help control blood sugar in diabetics and enable people to feel better about themselves. But the new research does suggest that dieting must be taken seriously by people at any weight.
N)It also means that dieting alone is not the best way to weight control. When a weight-loss program includes exercise, you lose more fat and less muscle, and you’re not likely to gain the weight back. That’s because exercise may help resist the physiological changes that tend to come from yo-yo dieting.
O)Given the potential risks of yo-yo dieting, anyone who diets should be especially careful not to gain the weight back. Before you diet, ask yourself how determined you are; then set reasonable goals.
P)Permanent weight loss should be the main goal, so select a program that will help you change your life-style. Be careful of popular diet programs designed for rapid weight loss and filled with senseless tricks, such as going on and off a diet, eating "magic" foods and so on. A program should focus on sensible changes in nutrition and life-style. The best approach is a low-fat, high-complex-carbohydrate diet and regular physical exercise.
Q)To avoid failing in the diet, recognize and plan for high-risk situations. If you always overeat when you visit your parents, for example, figure out how to get around that before your next visit. Understand that desires—for chocolate, say—are like waves that come up, will quickly subside. When the desire comes, get busy with a simple activity—reading or even brushing your teeth.
With each yo-yo, the time for the rats to regain became shorter and shorter.
选项
答案J
解析 题干关键词为each yo-yo和the time became shorter and shorter。文中J段提到，With each yo-yo，it became easier for the rats to regain．Alter the first diet，they took46 days to become obese again；atter the second diet．they took only 14 days．题于是本句话的高度概括，故选J。
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