Whether it’s from age or from losing a large amount of weight, loose skin is usually just an excess of subcutaneous body fat covered by skin. depending on your skin type, age, genetics, and many other factors, losing a lot of weight often means that your skin may not retract back to your small frame. When you lose a substantial amount of weight, depending on your skin’s condition, age, genes, and other factors, your skin may not retract back to your lighter body frame. SF Bay Cosmetic Surgery & Aesthetic Dermatology have treatments that involve devices that use radio-frequency technology to provide optimal skin contraction in the deep layers of your skin.