Don't be an enabler.
One of the worst things my OH does is bring chocolate into the living room in the evening to eat it, and offers me some.
When I complain about it, he tells me that he was brought up to believe that it was polite to share with people and he can't bring himself to be rude enough not to offer it to me, even though I have told him explicitly not to. I can just about manage to ignore him if he eats it in front of me, but I don't have the willpower to refuse if he actively offers it to me.
When I tell him this he tells me I am an adult woman and I am resposible for what I put in my mouth, not him - I can say no if I don't want it.
It is the only thing that really pisses me off about him.
He also doesn't understand about "allowing" yourself an off-plan treat, so he sees me eat a small bar of chocolate and then doesn't get why I am annoyed about him offering me chocolate. He buys me fattening things as treats "because he knows I love them" and thinks he is doing a nice thing.
I have tried to explain - I compared it to offering a dry alcoholic a glass of wine, in the full knowledge that that person WAS an alcoholic, purely in the interests of "being polite".
He is getting better, but he still doesn't really get it - comes of being 6 foot tall and effortlessly 150 lb - and never having lived with anyone with a warped relationship with food before.
What he does do for me is tell me I am beautiful and gorgeous and sexy all the time, and he looks after the DCs whenever I want to go for a run, and he came to support me when I did a 10K race last year. He is also proud of me and tells his friends that I run 4 miles a day every day - which is not true - it's more like 3 OR 4 miles about 3x a week.