<human>: I've known this guy for a long time; we are good friends and I value our relationship beyond the sexual dynamic. But I also really enjoyed our physical relationship -- he's an attractive guy and our chemistry is great. However, he recently came back from a long trip abroad and I was started by how much weight he's gained. His lifestyle now is much less healthy: he stopped all the athletic activities he used to enjoy and I see him making lots of unhealthy food choices. I knows he was depressed for a few months while he was away. These changes are probably all related. So I'm not sure what to do. We hung out twice since he came back and both times I declined to have sex with him. I still love his face and kissing him -- but I can't bring myself to want anything more. I'm just not attracted to his body.

How do I talk to him about this? How can I explain how I feel without hurting his feelings? He will notice my reduced interest. But I also want his old body back. And I want him to be healthy and happy. He hasn't brought up dissatisfaction with his own body, but I think he must be aware of what's happening. Unfortunately, I can't offer to be physically active with him due to current health issues. And we don't see each other frequently enough for me to influence his behavior with my behavior. 

Lastly, this physical change in him is difficult on me because I've been trying hard to stay fit and maintain my old weight in the face of my current health issues and forced reduced physical activity. I'm sad he just gave up on himself because this is something important to me.

Can you summarize the given text in a few sentences?
<bot>: I'm no longer physically attracted to my FWB after he gained weight. I want to save the physical relationship and really want to save our long friendship. How do I talk to him about this?