对身体极为有益的英文表达可以是"extremely beneficial for the body"或者"extremely good for the body"。这种表达源自英语中"beneficial"和"good"这两个形容词，它们都有"有益的"的意思。
下面是一些例句和它们的中文翻译：
Exercising regularly is extremely beneficial for the body.
(经常锻炼对身体极为有益。)
Eating a balanced diet is extremely good for the body.
(吃一个均衡的饮食对身体极为有益。)
Getting enough sleep is extremely beneficial for the body.
(保证充足的睡眠对身体极为有益。)