Obese people tend to sweat more due to having extra skin which folds over the other skin and produces sweat in between the folds. When sweat gets trapped it only keeps getting hotter due to moisture and wetness and this provides better environment to grow bacteria. This brings on the smell. They also have a problem getting every part of their bodies washed well due to being overweight.
Obesity also contributes to body odor, as many toxins are trapped in an obese body. These toxins are unable to leave body due to slow bowel movements and thus they are forced out of the body via sweat.
So if you are obese then clean your self properly as obese people needs to wash good, rinse well in the folds, dry with towel, dry with hairdryer in the folds and then apply Zeazorb-AF powder. Dead bacteria stinks no matter what unless it is removed from the skin. A hand held shower head is the best way to rinse in the folds.
For more details about preventing body odour read this