To understand how skin-firming treatments work, first you have to understand how skin works. Skin has three layers: the epidermis on the outside, the dermis in the middle, and the hypodermis, or subcutaneous layer, on the inside of the skin. For the purposes of keeping your skin firm, the layer you want to pay closest attention to is the dermis, or middle layer.
The dermis layer of the skin contains both collagen and elastin. Simply put, both collagen and elastin are types of protein that your body makes. They work together to keep the skin elastic, strong and moist. As you get older, your body doesn't make as much of these proteins, and the elastin and collagen that you do have don't work as well.
For skin firming to really work, first it has to reach the dermis layer of the skin. Any treatment that works on just the surface might improve the way skin looks, but it won't actually affect its firmness. Some effective treatments work by causing more collagen and elastin to grow, thus giving the skin more flexibility and strength [source: Mayo Clinic]. Other treatments remove or tighten skin, fat, muscle and connective tissues.
Many treatments can be done right in your doctor's office. To learn what these treatments involve, read on.