Amount of hype around milk and how it gets you fat is ridiculous. Milk does not get you fat, eating too much does. Obviously you have to understand Milk has quite alot of calories, if compared to in exampl. tap-water ( rip muricans, no tap-water ).
Sadly even here at Finland ( I thought we are smart ) we follow murica and our milk at school is basically water with milk taste and color(zero-fat, no milk-protein).
Same time you see teenagers visiting shops more and more, and buying candy-bars, all kind of sweeties and the fattest ones just buy some pie etc... Then we blame milk globally, lmao...
So if you eat like 100 KG man when you are school-boy and all you do is sit at school-desk and never workout you end up getting fucking fat. Eat less, better food, If you have to pay for lunch at school why dont you just make extra food everytime you ( your mother I guess ) cooks and pack it in a box. That way I can eat what ever I want in my work ( you can do it at school ) and it tastes awesome. In example, Chicken and rice and vegetables. Very good, and remove the sauces, they are liquid calories only getting you fat and providing zero help to your body( If you workout, or do sports ).
Btw, eating chicken and rice, If you eat that and get fat you have big problem. It fills you so much that if you eat it hugely surplus calories your stomach must be hurting and very, very filled.