Scientists have confirmed that the majority of overweight people who try to lose weight either by cutting calories or exercising will return to their former size．Fewer than 10 percent of the l2 million British people who go on a diet each year succeed in losing significant amounts of weight and most of those who do put it all back on again within a year．

    The study of 25，000 people provides further evidence of the popularity of‘yo-yo dieting’where slimmers get into a cycle of losing weight and regaining it．The scientists，from the Medical Research Council’s National Survey of Health and Development，have concluded it is better to avoid getting fat in the first place．They followed 5，362 men and women from their birth in l946 and 20，000 from birth in l958，measuring their weight and blood pressure and assessing their lifestyles．The researchers found both groups began gaining weight in the 1980s and have steadily increased in size ever since．

    Dr Rebecca Hardy，the council’s programme leader on body size，said：“0nce people become, overweight，they continue extremely upwards．They hardly ever go back down．A(印刷不清兩個單詞)  weight but very few get back to normal。The best policy is to prevent people becoming overweight．For men weight goes up steadily through life。For women it starts slowly and accelerates in the mid-thirties．”

   But the study's findings do not mean dieting is pointless，as eating less and taking more exercise can increase fitness and lower blood pressure．In 2009，a quarter of adults and l4 percent of children were obese(過度肥胖的)，according to the Department of Health’s latest Health Survey for England．Although previous research has shown one in four Britons is trying to lose weight at any one time，it has been predicted that 60 percent of us will be obese by 2050，leading to even more cases of diabetes(糖尿病)，heart disease and cancer．Experts said we are programmed to put on weight rather than lose it．Dieting can make this tendency worse as decreasing calorie intake causes the body to go into starvation mode and reduce the amount of energy it naturally expends，making it even harder to lose weight．Commenting on the study，Professor Nick Finer from London Hospital，said：“It is unlikely that man would have progressed with mechanisms to fight against obesity which has only become a problem in the last 30～40 years．For most of human history，storing fat would have been an advantage．”

 47．According to Dr Rebecca Hardy，which of the following is TRUE?

    A．It is easier for men to lose weight than women．

    B．Once people lose weight，they never put on weight again．

    C．Never to become fat is the best way of keeping a good shape．

    D．The fact that fat people keep their weight upwards is unusual．

  48．The author says “the study’s findings do not mean dieting is pointless” because    ．

    A．the study lacks believable facts

    B．obese people are confident in losing weight

    C．dieting can really make a few people lose weight

    D．dieting and sports help to keep people free from some diseases

  49．From the last paragraph，we can learn that    ．

    A．decreasing calorie intake makes it even harder to lose weight

    B．the idea that people lose weight with mechanisms is practical

    C．being overweight is a lasting problem through the human history

    D．by 2050 more and more people will have got unfit because of losing weight

  50．Which of the following can serve as the best title of the passage?

    A．Which is better：cutting calories or exercisin97

    B．Fat people can’t really keep the weight off

    C．A new study on people’s health

D．How to go on a healthy diet