When DH gained a bit of weight and was feeling self conscious about it, I told him I still found him sexy, but let's do something about it to make us both healthier and started cooking healthier and lighter meals.
I've come back from holiday last week having gained 4lbs, and when I complained to DH about it he said I look hot, but if I want to eat healthy this week, he's fine with that, and to let him know if I want him to be back from work early any evening this week if I want to go for a run/to the gym.
See, that's how people who care about the feelings of the person they live with deal with the 'am I fat?' question. You dont tell someone they are ugly and expect them to feel motivated to get in shape. What a cow.