I thought of tacking this one onto the "Why Exercise..." thread, but decided it would hang better here by itself.
In the spirit of a group of pictures is worth far more than 100,000 words see for yourself why muscle is better than fat:
http://www.google.com/search?q=density+of+fat+vs+muscle&rls=com.microsoft:en-US:IE-SearchBox&tbm=isch&tbo=u&source=univ&sa=X&ei=cwr7UZWMIoOVqQHvioCwBQ&ved=0CEsQsAQ&biw=1344&bih=682
In the spirit of a group of pictures is worth far more than 100,000 words see for yourself why muscle is better than fat:
http://www.google.com/search?q=density+of+fat+vs+muscle&rls=com.microsoft:en-US:IE-SearchBox&tbm=isch&tbo=u&source=univ&sa=X&ei=cwr7UZWMIoOVqQHvioCwBQ&ved=0CEsQsAQ&biw=1344&bih=682