OP, I have a DS who's 14-nearly-15. He's about 5'8", wiry, and just over 8 stone. I am telling you this just to say that I have experience with trying to get someone of his size into a car to go someplace he doesn't want to go. I'm 5'5" and while overweight also v. muscular (used to play rugby). If my DS were seriously fighting me, it would not be possible for me to get him to, let alone INTO the car without injuring him. Matter of fact, even when he's "play" fighting me I can't move him more than five or ten feet without putting him in a fireman's carry, and it would be really easy, if someone were fighting, to wreck my back that way.
Now, as far as your DS' current and past weights, and his patterns of putting on weight. Don't look around at other boys his age, they don't matter a jot. The people you need to look at are his male biological relatives: your father/brothers, his father and GF and uncles, etc. My brother was so "obese" that he was clear off the growth charts until he was twelve. Then his growth spurt started. When he finally got done at 19, he ended up at 6'2" and 11 stone, and that has been his weight since, no matter what he does or does not eat or his level of exercise. My DS was VERY chubby in a manner similar to his uncle but I have never restricted his eating, just provided appropriately healthful food for him. In his 13yo yearly physical he was 5'3" and 7 and a half stone. So, in less than two years he's gained five inches height, but less than a stone in weight. Do you see why I'm saying it's more important to look at familial growth/weight patterns?
I agree that boys of 14 can be horrible sometimes, but it's our job as their parents to teach them how to interact appropriately with us, their peers and their teachers. It's also our job to model for them how to eat healthfully. A 14yo boy who is growing feels like he is STARVING and his body is telling him to get energy from anywhere possible and they are probably not psychologically capable of "learning to moderate eating". The quickest energy is from carbohydrates, which is why he's going after bread and sweets. My DS can put away alarming amounts of food in a day! I simply accept that he needs that energy to grow and focus on providing it in the form of lean protein, fruits and veg as much as possible. (And no, I'm not a wonder-mum by any means; my DS is also very sedentary and tbh I could be doing a lot more in terms of getting him out playing sport and building muscle.)
I really fear that if you were to send him to a "fat camp" you would put him in danger of acquiring a disordered relationship with food (note I did not say an eating disorder) that will remain with him for his entire life. You would do him a much bigger favour by making a change to healthier food in the house and sharp-focusing instead on the reasons behind his obnoxious behaviour.
Best of luck to you and your DS!