People are overweight for many reasons, the most important one of which is that they eat t

People are overweight for many reasons, the most important one of which is that they eat the wrong foods, get the wrong types of calories per meal, and they also eat meals at the wrong time each day. Food is more powerful than any weight loss pill, because the food that you eat can either make you thin or fat. This is true because your body is like an engine, and it only needs certain foods at certain intervals(间隔)each day.
Low-calorie Diets Do Not Work 
The reason people cannot lose weight by starving themselves is that their metabolism(新陈代谢)will detect any major drop in calories and it will then adjust(调整)itself by burning fewer calories each day. That is the reason why you can eat 1,000 calories per day and not lose any weight, while your friends can eat 2,500 calories per day and not gain any weight.
Low-fat Diets Do Not Work
Many people in today’s society are buying mostly low- fat or non-fat food at the grocery store. Everybody knows how much fat is inside the food they buy. However, people are getting fatter than ever before by doing this. They are not losing weight by changing to this low-fat lifestyle.
Losing weight has nothing to do with these things. One of the most important things you can do to control your weight is to eat the proper foods, such as fruit and vegetables, eat them at the right time, and exercise every day. If people make this a habit, they will lose weight.
68. What is the main reason why people are overweight according to the author?
A. They eat the wrong foods at the wrong time.
B. They eat food with lots of calories.
C. They don’t take any weight loss pills.
D. They burn many calories every day.
69. The article is written in order to     .
A. tell readers not to buy low-fat or non-fat food
B. tell readers how to lose weight
C. tell readers about an important scientific discovery
D. call on people to lose weight and stay healthy
70. To realize the aim of your weight loss plan, you should     .
a. do exercise every day      
b. eat meals at the right time
c. eat fruits and vegetables   
d. eat low-fat or sweet food
e. eat the proper foods at each meal
A. a, b, c, d       B. a, b, d, e     C. a, c, d, e       D. a, b, c, e 68---70   ABD