IDK if it is universal but once I hit 20s I gained weight rapidly despite eating same. Most of my friends gained weight too. Obviously puberty ends and metabolism drops but I feel like for me it's on the drastic end. For me to stay lean and not skinny fat means either eating not the tastiest food like lots of vegetables or being in the state of slight hunger for the rest of my life.

It feels like there is a pick 2 situation between lean body, being full of energy and being satisfied by food