Eli5 Why do lips get thinner as we age?



I can understand why skin sags and gets wrinkles but eli5 why/how do people’s lips get thinner and thinner as they get older?

In: Biology

Lips are mostly collagen and estalin. Our body produces less of these as we age (which leads to sagging skin in general), so our lips start to appear thinner. There isn’t much you can do about it, it’s just one of those things that happen as we age.

Edit: I should say that collagen and estalin are what make our lips appear plump and full.