因身体欠佳 怎么说？

由于身体欠佳，他现在较少参加社会活动了。
He is now, owing to ill health, not so active in social work.
他想参军, 但因身体不好被断然拒绝.
He tried to join the army but was turned down (flat) because of poor health.
听说您最近身体欠佳，心里很不安。:
I am very sorry to learn that you have been ill for some time.
她身体欠佳已有些时日了。:
She has been in delicate health for some time.
身体欠佳的状态
in a low state.

due to I'm under the weather

due to 由于
under the weather 身体不适

Because body unsatisfactory

due to health reasons，...

because I am in a bad condition.

I feel not well. I don't think I feel comfortable. I feel myself not comfortable now. I think I am ill.