I don't think desiring our spouse to be healthy, and then voicing that concern, is a bad thing. Even if the one voicing it is overweight, it doesn't negate the fact that they both need to lose some pounds. My uncle-in-law's wife is incredibly obese. He's not a healthy size either, but she outweighs him by, at least, double his weight. It's not a healthy way to live and, I apologize if this is offensive...but no one should live like that. The Bible says our bodies are the temple of the Holy Spirit, and that the things we do to our bodies can defile the temple(fornication, inappropriate content, drunkenness, etc.) Living at an unhealthy size(whether obese or super slim) is wrong. Notice please that I said "unhealthy size". There is no universal "healthy" size. My mom is not skinny right now, but she is at a healthy size for her age and body type. So please don't assume I'm saying everyone needs to be a size three.
I know many people who get offended at the idea of their husband potentially being unhappy with their body. In every case that I have seen it hasn't been because the dissatisfied spouse is a nitpicky jerk who can't stand five extra pounds, but rather it's been that the obese spouse is getting to or has reached the point of being very unhealthy and the other spouse is in fear of their health and safety. If the dissatisfied spouse is overweight as well, then they need to lose weight too, but that doesn't mean the other is off the hook either. Being healthy is something I believe we should all strive for, and not just in body weight. There are other aspects of health besides weight. I'm a small person, but I don't eat as healthily as I should. That's not right either.
Another common assumption is that one can't be healthy until they've reached a certain size. But that's not true. A healthy size for me is not going to be a healthy size for someone else. I'm short and petite. My mom, for instance, even when she was young, was never my size. It's not possible. But, she can reach a state of healthiness that still looks just as good as I do, even though she'll never be my size. And she can hide an extra few pounds better than I can. I gain an extra pound and it shows. Grrr.
DH has told me that he will never let me get to the point of being as obese and his aunt. And yes, part of it is because he loves my body and doesn't want to see it ruined. I'm not offended by his statement. In fact, I'm glad he feels that way. Would he still love me if I were obese? Yes he would. Would he be wrong in wanting me to get healthy? No he would not.