Ok, so first of all - marrying is the first stupid decision he's about to make... Fattie, well - it's almost inevitable she'll get fatter as the time goes on. He either must be a lover of chunky ones or he may accept that he'll cheat on her with /in shape/ bitches after like 3 or 4 years down the road.
These, saying that skinnies are all about diets, etc.. well it may not be the case if a girl has a genetic predisposition to be skinny (then some fat that she would accumulate out of sitting on her lazy ass may look even good). To be able to "calibrate" - lookd for small ankles/wrists, generally - small joints and long skinny fingers.
Find a skinny girl that had no father figure in her life, then become one, and she'll be your slave till you'll get bored of her and move on to the next victim. While marrying a fattie should be a very very well thought out decision not to find oneself in a trap of few annoying kids and a whale on the side with no way out (plenty of fellas like that, just look around. They usualy say "Yeah man.. I'd like to bodybuild/and this and that - sooo much.. I'll come to the gym next week, aiight?" and they never come...). It's a dangerous risk.
