Read the following passage and choose the best answer (A, B, C, D):
Thanks to our modern lifestyle, with more and more time spent sitting down in front of computers than ever before, the number of overweight people is at a new high. As people frantically search for a solution to this problem, they often try some of the popular fad diets being offered. Many people see fad diets as innocuous ways of losing weight, and they are grateful to have them. Unfortunately, not only don't fad diets usually do the trick, they can actually be dangerous for your health. Although permanent weight loss is the goal, fewareabletoachieveit. Expertsestimate that 95 percent of dieters return to their starting weight, or even add weight. While the reckless use of fad diets can bring some initial results, long-term results are very rare. Nonetheless, people who are fed up with the difficulties of changing their eating habits often turn to fad diets. Rather than being moderate, fad diets involve extreme dietary changes. They advise eating only one type of food, or they prohibit other types of foods entirely. This results in a situation where a person's body doesn't get all the vitamins and other things that it needs to stay healthy. One popular fad diet recommends eating lots of meat and animal products, while nearly eliminating carbohydrates. A scientific study from Britain found that this diet is very high in fat. According to the study, the increase of damaging fats in the blood can lead to heart disease and, in extreme cases, kidney failure. Furthermore, diets that are too low in carbohydrates can cause the body to use its own muscle for energy. The less muscle you have, the less food you use up, and the result is slower weight loss. Veteran dieters may well ask at this point, "What is the ideal diet?" Well, to some extent, it depends on the individual. A United States government agency has determined that to change your eating habits requires changing your psychology of eating, and everyone has a different psychology. That being said, the British study quoted above recommends a diet that is high in carbohydrates and high in fiber, with portions of fatty foods kept low. According to the study, such a diet is the best for people who want to stay healthy, lose weight, and keep that weight off. And, any dieting program is best undertaken with a doctor's supervision.
1. What is the author's main point?