Don't go on a diet.(不要節食。)

He has been on a diet for as long as any of his friends can remember.(從他的朋友能記得時開始，他就一直在節食。)

I'm on a diet.(我正在節食中。)

I'm forever on a diet, since I put on weight easily.(我一直在節食，因為我的體重很容易增加。)

I can't eat too much, I'm on a diet.(我不能多吃，我在減肥。)

He has been on a diet for 12 weeks.(他已經持續節食十二周了。)

No. I'm on a diet.(不要了，我在減肥。)

We existed on a diet of rice.(我們靠吃大米過活。)

I'm supposed to go on a diet.(我應該節食。)

People who are on a diet mustn't have chocolate.(正在節食的人不能吃巧克力。)