I exploded in size as soon as I hit puberty and have never been able to take off the weight. I ate the same foods as my brother and we did roughly the same acti

I exploded in size as soon as I hit puberty and have never been able to take off the weight. I ate the same foods as my brother and we did roughly the same activities. Puberty was a night and day switch from scrawny kid to fat kid and it’s been a constant challenge since. My son is desperately trying to gain weight for a dirty bulk. He’ll put down a full pizza by himself in a night and has to force himself to keep eating more calories. When we go out to eat he picks meals based on what has the most calories. He’s still a rail and can’t keep on weight. And apart from lifting 2-3 times a week for roughly half an hour he’s completely sedentary so he’s no expending a tremendous amount of calories through other activity. For some people, staying thin is just their normal and not some diligent attention to what they consume.