All the weight-lifting in the world won’t build up enough muscle to pick up the excess skin that can hang and flap under the arm, particularly if you have lost a great deal of weight or have a tendency to gain weight in that area. Excess fat in the upper arms can sometimes be reduced through liposuction alone, but loose, drooping skin may need to be excised. To that end, an arm lift is an impressive way to shore up that area, making the skin smooth and taut again. Incisions are hard to hide for this operation, because they can run lengthwise from the armpit to just above the elbow. The risks for this operation are the same as for the tummy tuck procedure.