Losing a bunch of weight — whether it’s through diet and exercise, surgery, or a combination of different approaches — isn’t all glitter and smiling “after” photos. If you shed a significant number of kilos, having loose skin is normal — and extremely common. Also normal? Feeling a little bummed about it.

“This is a legitimate concern that patients have when seeking obesity surgery,” says Dr Vivek Prachand, a bariatric surgeon and associate professor of surgery at The University of Chicago Medicine.

Why does loose skin after major weight loss happen? The maybe-a-little-downer (but real talk) truth: If you were in a larger body previously, excess fat likely stretched out your skin. Couple that with the fact that collagen and elastin (an elastic protein) in the skin naturally decrease as you age, and you’ve got a recipe for excess skin, explains Dr Manish Shah, a board-certified plastic surgeon in Denver.

“There may not be sufficient elasticity for the skin to contract back down to your new, smaller body size,” says Dr Constance Chen, a board-certified plastic surgeon in New York City.

Stretch marks are one sign of skin being, well, stretched past the point of no return: Once you see them, “it’s much more likely that significant weight loss will result in loose, hanging skin,” says Dr Chen.