I'm confused

I just don't get it. When I watch tv I see these girls on shows. I mean teens who are skinny and pretty average and they end up on these diets. Like crazy diets. For example they don't eat for 3-4 days and then they faint or something bad happens to them. At that moment I ask myself this question. Why are they trying to be slim? They already so skinny. I just don't get. Why do tv show writters make this type of shit? Excuse my language. Like if they are going to show something like that. At least the person be a little over weight or maybe have some fat! Like I'm not the skinniest person. I'm actually overweight but watching this makes want to cry. And wonder do girls in real want to lose weight when they have no weight to lose? My advice to whoever reads this is to tell teens like that to cut it out. Like stop. YOU ARE NOT FAT. Trust me. I know what it means to be fat.