Re: Penis size
Being overweight will affect your flaccid (soft) penis size. There is a pad of fat just above where you begin to see the penis protrude from the body, and as that pad grows it will make the penis appear smaller. Losing weight can and usually will "increase" flaccid size, but note that it is all cosmetic - nothing about your penis size truly changed.
The only other way being overweight might affect penis size is in hormones. The current theories about penis growth point to testosterone levels being one of the key factors. It is a well known fact that men who exercise regularly and keep their bodies in good physical condition tend to have higher levels of testosterone than men who don't.