My best friend is the same way. She constantly tried to get me to eat the wrong things pre-op. She seemed to be trying to sabotage me. I asked her to go to a support group with me. She listened to the pre and post op people throughout the meeting. They had wonderful insights about the journey. I asked them about what she was doing. They were very helpful in explaining to her what was happening to me and why offering me food and telling me I hadn't eaten enough was hurting me. She finally "woke up" that surgery is my choice and whatever comes with it. If your man won't listen to you maybe a group of people at a support group will open up his ears.
Be strong. Put that box of candy in a place you won't have to deal with them until next February and then regift it back to him from your skinny self...
You are very welcome. I know how difficult it is being a caretaker and how stressful it is. It is rewarding, though. It might not seem like it now. You can do this, you are not alone.