I'm 5'9 and like 135 pounds.
I'm not fat, and I'm not skinny.
I got a six pack, dece biceps, and lots of muscle in my legs + quads.
If he isn't fat, you don't want to overwork yourself.
But when your fat, you don't want to overwork yourself either. You might have a heart attack. I think he should just wait a little while till he gains a few extra pounds.