这三个词均可表示“健康的”，不过也是有区别的。

1. 从句法上看：healthy 可自由地用作表语或定语，well 通常用作表语，但在现代美国英语中有时也用作定语，而 fit 则多用作表语（偶尔也用作定语）。

2. 从含义上看：healthy 主要指一个人身体强健、很少生病，尤指一个人长期的健康特征；相比之下，well 则通常指人们在特定场合下的健康状况；fit 表示健康，尤其指由于锻炼所导致的健康，它可指特定的健康也可指长期的健康。如：

Though he is 80 years old, he is still healthy.

You don’t look very well.

The children are quite healthy although they have slight colds at the moment.

Exercise keeps you fit.

He runs to keep fit.

Are you completely fit again?

3. 有时 fit 可与 healthy 或 well 换用。如：

Keep healthy/fit, study well and work well.

I’m not feeling very well/fit this morning.