18 and in college - I have one of those!
Sorry mom...at 18 and in college? If he lives at home give him physical chores - washing the cars, taking out the trash, mowing a lawn (a push mower is great), cleaning the pool. Only stock fruits and vegetables in the house. If it comes in a wrapper don't bring it in.
Living at school? Don't send care packages that include food or fast food cards. And...that is it. He is 18. We had 100 percent food control from birth to middle school and from middle school to high school we had 80 percent control.
When they are in college and 18, you hope for the best.
You could have pulled strings - get him in a dorm furthest from classes, helped pick a hilly college in an active state.
It's hard! I have wanted to be more involved in my kids college life, but you just have to pray and let them know you are supporting them.