I like to stay in good shape.

我喜欢保持健康的体能。

I want to lose weight.

我想减肥。

You are not overweight at all.

你一点都不胖。

You should lose weight by exercising.

你应该透过运动来减轻体重。

You need some workouts to lose weight.

你需要运动来减肥。

You should go on a diet.

你应该减肥。

Try to eat less from now on.

现在开始，试着少吃一点。

Don't eat too many snacks now.

现在不要吃太多点心。