First thing is to take him aside. You obviously don't want to do this at the table with everyone else present.
Once you've got him alone just say: "I'm sorry I have to tell you this, but your body odor is disturbing the other players."
If you think that deodarant will help, offer it to him. Else ask him politely to go home and fix it before coming to play: "I'm afraid I have to ask you to come back after you've taken a shower and changed your clothes."
He's probably unaware of the problem himself. The odor is around him all the time, so he can't smell it anymore.
Good, subtle advice here, but it lacks the comedic impact of this suggestion.
i had to tell someone that before. took them outside, and started off by saying "one of us stinks, and it isn't me."