To lose weight,you must use or burn off more calories than you take in.

VOA: special.2010.06.08

As we'll discuss in the class, and most of you probably know this, your body weight is a function of how many calories you take in and how many calories you burn off through metabolic processes but also physical activity.

我们将会讲到,而且你们中的大部分人可能也知道,你的体重随着卡路里的摄取量,和代谢中的消耗量而变化,还跟肢体活动有关

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

Eat fewer calories and increase your activity so that you burn off more.

VOA: special.2010.06.08