While I wouldn't of included all the details the OP did. It would be incredibly hard to find out who this kid is. Anyone who is trying to do that would have to do a lot of cross-referencing and would be creepy for doing so.
I can tell the OP is new to DCUM just based off the writing. None of the common abbreviations are used.
Now, getting back to the topic. Gaining weight in college is incredibly common for men, especially at state schools with big party cultures. My son graduated college a year ago and came home roughly 100lbs bigger than when he started. Now, my son was 6' 150lbs when he began college and I assume he's sitting around 250 currently.
I understand the OP's pain with this, my son was very active in high school (he ran cross country in the fall and played lacrosse in the spring) and was always super lean growing up. At 6', 150lbs, he was underweight and I was glad to see him come home about 30lbs heavier after his freshman year.
The issue is that once they develop these bad eating habits/don't care about the weight gain, it just gets worse. My son joined a fraternity as well and the amount of partying/constant junk food eating did nothing good. He ended up graduating college at roughly 250lbs due to continuing to eat like crap and not caring about the weight gain. My son works out but it is mostly lifting, so he has a lineman type build now which helps him carry the weight well.
OP, I never said anything to my son about this though. He is an adult and is well-adjusted. Like another poster said, be grateful you have what seems like a great kid!