Alot of these comments don't help at all so I hope this one does.

Be straight up and direct. Tell him to stop with the games for 3 months. Don't be easy about this, it isn't healthy at all and if he'd rather game then he'll lose you... 3 months to eat right, get fit, get into good sleeping pattern, work well and focus, clean and cook with you and go out to do errands.

If he'd rather eat some microwave meal, play games till 3am and do f*** all work then he can have all that and you'll leave.

He yells at you? What in the what. I'd never yell at my Gf and I couldn't even imagine myself doing it. That's so bad and the beginning of an abusive relationship.

If he does the 3 months to change then good throw it all out after the three months. If he truly loves you then this will all be no problem at all. Don't compromise on anything because already for a long time you've put up with a child who is supposed to be your man. He's acting like a damn fool. Anyway hope it helps.