Unsightly underarm fat is much more common in woman than in men. This is simply due to the fact that men typically do more heavy lifting than woman and have more developed muscle instead of fat. If your underarms are not properly toned, you are much more likely to have extra arm fat and even extra skin. The three major causes of arm fat are:
Family Genetics - Take a look around at your next family reunion, is underarm fat common on your aunts and cousins?
Being Overweight - Extra fat in your body must reside somewhere; your underarms is a very common place for it to build up. You may have toned muscles underneath your fat.
Lack of Muscle Tone...