on a diet 控制饮食
OK. It's official. I'm on a diet for one month starting today!
好，我决定了。我从今天开始控制饮食一个月！
cut back 少吃
Are you sure? We're all supposed to go out for pizza tonight.
你确定吗？我们今天晚上都准备出去吃披萨的呀。
