go on a diet （为了减肥）而规定饮食；节食
例句：
Mary went on a diet and lost four pounds.
玛丽因为节食瘦了四磅。
I'm gaining weight.I must go on a diet.
我的体重在增长，我必须要节食。
The doctor said I am a little overweight.So I should go on a diet.
医生说我有点超重，所以我需要节食。
背景音乐：
Glee Cast-Saving all my love for you
