Outrider wrote:
Never mention her weight.
Ever.
Always blindly agree with her when it comes to her weight, even if you are right and she is 'wrong'.
If she says she's trying to lose weight, yet still eating extremely unhealthy and eating lots of snack and junk food every day, all the time, you keep your mouth shut.
Don't even try to subtly suggest she cut back.
There are other, far more sneakier things you can do, like Fnord says.
Learn to cook and learn to cook healthier meals for her. Ensure you serve her portions that aren't too high.
If she's going to snack on junk foods, maybe don't intentionally buy any yourself and leave it up to her.
This is easy if you are me, as I eat extremely healthy and if I had a girlfriend and shopped for groceries with her, I would NEVER pick-out any snack foods as I never eat snacks.
Any snacks that would go into the weekly groceries would be her doing and not my own.
It might slightly have an influence, as it may mean less junk food being bought, and if she were to ever complain there's too much tempting junk food in the house, while not insulting her for her weight, you can be honest and say you didn't buy ANY of it.
Either way, if she says she aims to lose weight while scoffing down her fifth serving of mcdonalds and alcohol for the week, simply say "Well, I don't believe you're overweight at all, but you have my full support in your goals, but just remember I'll love you just as much and all the same if you find it too hard, which I very strongly believe you will not, as you are dedicated and hard-working."
I've found this is a good way to keep friendships and relationships - simply agree with the other person, pretend to listen to whatever trivial matters they may whine about or rave on and on about.
These are their 'flaws', and if you can learn to deal with them and look at their positives, than it makes things so much more easier.
Fnord/Outrider, have you ever mentioned weight to a wife/girlfriend, how this went?