The energy value of the food we eat is counted in calories. The average man requires around 2500 to 3000 a day. This varies with age, build and activity. Overweight occurs when the input of calories is greater than the output. To lose weight, you must take in less than you need—when you do this, your excess body fat is used for energy.

(64 words)

　　Which of the following is the best title of the passage?
　　 A) How to lose weight.　　　　
　　 B) Reasons for overweight.　　　　
　　 C) Calories and weight.　　　　
　　 D) Energy is the most important thing for people.
　　　　

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