I knew a guy that was extremely fit. His wife was a friend of mine and she told me before I even met him that he had an odor problem. Once I met him...I smelled him immediately. And he just got out of the shower and had on fresh clothing. He had gone to doctor after doctor trying to find out why he smelled so bad and none could give an answer.
My friend and I tried everything to help this poor guy out. Odor also comes from clothes not rinsed well enough in the wash cycle. So we washed all his clothing once, rinsed twice. Still didn't work. Eventually one doc said that sometimes sweat glands get clogged with bacteria and that is the smell he seems to have a problem with.
Point being, having flab does not mean someone stinks. Unless they have poor hygene habits.