Hello!
I'd appreciate a reply and explanation regarding my following question.

Is it possible to use the verb "SUSTAIN" in such a combination:
"to sustain a good body shape''?

Question

Hello!
I'd appreciate a reply and explanation regarding my following question.

Is it possible to use the verb  "SUSTAIN" in such a combination: 
"to sustain a good body shape''?

Answer

Yes, that phrase is perfectly fine.

'Sustain' here means keep/maintain.