You like a guy but are worried that he is fat? It is great when you can still be superficial about someone's appearance. Answer is depending on his lifestyle...he could be 6' out of shape pants size 34 and have a gut. Sounds like this guy isn't skinny, but I doubt he is grossly overweight either. I hope he realizes he can do better than some silly girl who would judge him by the inches of his waistline.
If looks are that important...you should not be shopping men, "Sight unseen"