I have taken notice that almost every single person's face structure changes a certain way after they go to prison

The cheeks go flat, there's something about the cheeks. It's not really sunk in like they lost weight it just changes this certain way. A guy I really care about went to prison yesterday after being held in jail for over a year. I've wondered this whole time if his face would form the way I've seen it in other people before and I just saw his mug shot today and it has!! Not only the cheeks but he doesn't have that same twinkle in his eye it doesn't even really look like him. Have you ever noticed this? And what do you think would cause it?