How to deal with boyfriends insecurities?

me and my boyfriend have been together for 2 years, i plan on marrying him, having kids, the whole picket fence and 9 yards. but since we started seeing each other he's always been very insecure about us, because he is over weight and i am not. i don't see a problem with his weight, and i never have, i think that he's the sexiest man alive. but he always asks me if i still love him almost on a daily basis for the past two years. at first it was endearing i guess because he thought so highly of me, but now i can't stand it to the point that i don't even want to talk to him when he's like this. and everyday it's a new insecure question, and i've brought this up to him many times, and every time he tells me he'll try to stop, and i tell him how much i love him, and think he's the sexiest man alive. but after a few days he's back to asking me if i still think he's sexy, if im cheating on him, if i think we'll be together forever ect. what do i do!?