4 Things to Stop Doing Once You Turn 35

What you used to do: Your dress size probably fluctuated over the years and even season to season (winter bod is a very real thing for you).

Why that's a bad idea now: Estrogen levels can start to decline in your mid- to late 30s, which leads to fat redistribution throughout your body, including your face. For most women, that means a loss of volume in the cheeks, says Wu. Add significant weight changes on top of that, and you could be dealing with less-than-youthfully plump cheeks and looser, saggier skin.

What to do instead: At the risk of repeating something your doctor has probably told you a million times, get to a healthy weight and stay there. Going up and down by a couple of pounds won't negatively affect your face, but repeatedly losing and gaining 15 to 20 pounds probably will.