I don't know how to talk to my boyfriend about his body?

I didn’t quite know how to word the question, but I can explain so please bear with me through my explanation and wait until the end to formulate an opinion.

So here is how the story goes: I am a 5’9” female, 125 lbs, pretty slender. I’ve been told I have a very nice frame. My boyfriend is 5’5” on a good day and overweight. He was obese during his childhood (middle school) and lost weight during high school. He is much smaller than he used to be but still has a little bit of a way to go before he is a proper weight for his height (about a 30–40 lb loss). He has been this way since before we started dating. Now before I continue, I want to make it clear that I do not want to break up with him. But here is the issue….my boyfriend lately has been asking me questions about how much I’m attracted to his body and what I think about it. These questions are hard for me to answer because honesty is something we both value but at the same time I don’t want to hurt his feelings. My honest view: I’m not attracted to his body at this point in time. I do not think overweight is attractive, and I do not like the extra weight on him. So you may ask, well why get with a guy that you aren’t attracted to in the first place? The thing is, it’s not that I’m not attracted to HIM, it’s just his body. I think he has nice arms, shoulders, frame, and VERY cute face. He’s like the perfect mixture of cute and handsome. Has almost a baby face, but at the same time a very masculine jawline and prominent nose. I got with him despite my lack of attraction to his height and weight because I loved him on the inside. We connect on a deep level, have the same values, and I can talk to him about anything. He treats me well and I have never met anyone else that I like more than him. Have I met more physically attractive men? Yes. But I have not been attracted to them in that way because of all the other things I love about my boyfriend. It’s not like he’s ugly; he’s attractive, just big. However, he keeps asking me these questions and I feel horrible because he can tell I am not 100% attracted to his body the way he is to mine.

To an extent, I know it isn’t fair. It’s hard for me to see it his way because I have always been skinny. I exercise and can eat whatever I want and actually have a hard time gaining weight. He is the opposite though. He eats and drinks much healthier than I do and exercises even more, yet it’s incredibly hard for him to lose weight. I WANT to be attracted to his body, but I can’t help what I like…...I don’t think that a whole lot of people just think that “fat” is sexy, but are with their partners despite that because they love them. That’s my situation. I love him despite his weight, and I want to stay with him. I think it would be stupid of me to break up with such an amazing guy because of how heavy he is. Physically attractive guys are easy to find, guys that are completely attractive on the inside are not. But I am not attracted to his weight specifically. I do not know how to say this to him though without hurting his feelings. Lately he’s been getting down on himself and I don’t know what to do. I’ve told him about the particular things I like about him (like his shoulders, arms, etc), I never insult him, but him consistently bringing these questions up is making things difficult. How do I address this situation and boost his ego while at the same time keeping him from being self depreciating and depressed about his appearance?