As age and gravity take effect, the back and upper arms tend to become flabby and drop fullness.( batwing arms) For this reason, I try to encourage women to do arm liposuction earlier, as opposed to later in their lives, if there is disproportion in this area. By reducing the amount of the fat in the area and tightening the skin with proper technique, the posterior upper arms stay tighter and more defined as time passes.