我很担心你""""的"""""身体。It sounds more nature. You can use "I'm worried about" as following . He eat junk foods everyday , 我很担心。 He have been single for 3o years , 我很担心。 Problem + 我很担心。 我很担心+ XXXXXX

no, must add 你的 身体

Sometimes,yes. But, is the premise. Cause if you just say "I am worried" ，people will have no idea what you are worrying about.