[PleasantlyFascinated]

don't get it, really I dont. Increasing muscle mass????

Of course.  What's not to get?
Muscle = health and vitality.  I like my women to be healthy and vital.  I like to be healthy and vital, whether to feel feminine or to feel male.  Bone structure makes the frame, muscle sculpts the body to its natural shape of beauty.  Fat obscures the beauty that muscle and bone have made.