Thank you for your question about when a back lift is needed for excess back skin after weight loss. Given your history of weight fluctuations and now permanent weight loss, your skin has experienced multiple changes over the years. Since your skin's ability to rebound naturally may not be as it was when you were younger, I believe you would benefit more from a back lift than from counting on your body's ability to snap back. There are two main types of back lifts: horizontal and vertical. A horizontal lift involves a horizontal incision across your back, from the outer corner of one breast to the other, after which a large flap of skin and fat is removed from your back. The end result is a linear scar across your back. With a vertical lift, an incision is made from the armpit down your sides, and a large amount of skin and fat is directly removed from each side, creating an hourglass figure. Both types have their merits, and your recovery posture (on your back) will be important in either case. I hope this answers your questions regarding when it's better to opt for a back lift over relying on your skin's natural elasticity.