I think it's safe to say that most people want to date or relationship with someone who is healthy enough. For me, it's not about being the healthiest person around, just healthy enough. I don't want to date someone who is close to death, or I feel could be close to death because of their health.
I like to think I live a healthy lifestyle, but I could do better for sure. Most women I date are fairly healthy. I haven't dated anyone who I thought looked unhealthy. If there is ever a time where my girlfriend gets unhealthy, I will try to help her through it. It's not like I won't help through that process, as I would ask for help if I gained a lot of weight or something, or had other health conditions. Now if someone is sick and isn't trying to fix their situation, I can't do that. I will try to help, but if she doesn't want to get healthy again, then I don't want to be a part of a relationship like that. And I would see that being the same if I were being unhealthy and unwilling to better myself.