You need to diet to watch your weight.

你需要节食来控制体重。

It is not the kind of food you want to eat if you are watching your weight or trying to be healthy.

如果你比较在意你的体重或是试着健康饮食，那么它不是你要吃的那种食物。

That's why they are sort of dangerous if you are trying to watch your weight – that is, you are trying to make sure you don't gain weight.

这就是为什么如果你试图观察你的体重，它们有点危险——也就是说，你试图确保你不会增加体重。

A large number relied on nothing more sweet rising than brisk walking on the equipment, from, though they don't seem to be one item that will give you a definite age when you're watching your weight.

很多人都是在健身器材上快步走起来的，不过他们似乎并不能在你关注体重的时候告诉你确切的年龄。