Urgent weight loss help?

please help my cousin is 15 years old 5 foot 8 inches and weigh 310 pounds, I just went to see him 3 months ago and he weighed 290 pounds. He will not stop eating he goes to macdonalds at least once a day and gets to double quarter pounder and a large fry. The doctor says he has high blood pressure and high blood sugar. He said he could be a type to diabetic within a year. And I also have a friend and 2 years ago he used to be 5 foot 7 inches and 150 pounds, he was a very muscular guy and all the girls liked him. But 2 years later he is 6 foot and 305 pounds and has high blood pressure I want to help them he wears a size 46/34 pants and 3 xl.(wore a 44 last week but at school the on flew off). And my cousin wears a 48/30 and a 3-4xl shirt, I want them to be healthly because I like to hang out and have fun with them, for example me and my friend used run 2 miles everyday after school now he can barly run 100 yards. And my cousin still plays football but baley can evn run any more.