I am just
at how many people think that it's absolutely fine to insult your partner!
A while ago, DP and I both put on a stone or so (I went up to a size 14 - I'm 5'8"). We both agreed we'd got a bit chubby, and we ate healthy low GI stuff until we lost the weight. But if he hadn't wanted to, and had carried on gaining weight, I'd have told him that I was concerned about his health, and if he continued to get bigger, I'd have told him that I was no longer finding him attractive. If he chose not to act on that, then ultimately that is his decision, as he is an adult and can make his own choices. If I didn't want to sleep with him because I didn't find him attractive, then I'd tell him how I was feeling. I'd expect the same in return.
But I would not insult him, make jibes about his weight, and endlessly nag him, and I wouldn't call him a grotesque fat pig or repeatedly tell him that he's ugly.
If I had so little respect for someone that I could speak to them like that, then I would rather leave them than carry on in the relationship, frankly. And if anyone spoke to me like that, they'd be out on their ear. 