N's love commenting on our weight. Most N's are very lazy. In my experience, it's the very lazy or not very bright that focus on a person's weight as a means of putting them down/controlling them---it's outward and easy to devastate a person that way and it takes very little work to wield that weapon. People who do this are assholes, plain and simple.
As for Christmas, stay at a hotel if you decide to go back. If anybody tries to go in about your weight, pick something awful about them that they'd be self-conscious about and ask them if they'd like to talk about that. My NMom constantly picked on my weight, but I finally shut her up during one of my own Christmases visiting.
NMom: You look like you've gained weight... Me: You look like you're balding in the front! Like, really bad. Wow. What's that mole? Is it skin cancer? It looks like it's grown since last I saw you...
Mean? Perhaps. But effective.
My NMom was obese. My NDad was obese. Guess what? They had obese kids. But that was all our fault and we needed to "stop being fat" because we were "making" them look "bad". Um, newsflash, if you are the parent and your child has a weight problem, it's your fault. They're not in control, you are. You do the grocery shopping, you probably plan the meals (though I was responsible for making dinner starting when I was about 6, but I cooked what I was told to). I didn't know vegetables were to be eaten other than on Thanksgiving, Christmas, and Easter. My Nparents had atrocious eating habits and they passed that onto us.
That being said, from the time I was around 8, my NMom told me that I was so fat that I would never have friends. She said that I was so fat that no man would ever love me. She said that it was such a shame that I had such a pretty face attached to such a fat body. When this started, I was 10lbs. overweight. I'd been fine until my NMom pulled me from dance class and gymnastics because she needed me to raise my baby sisters while she chain smoked and sat on her ass all day. I wasn't allowed to leave the house because I was "the help". Without exercise, I gained weight. At one point when I was in 5th grade, my NMom decided to take an active part in my weight loss and put me on probably about a 500-600 calorie a day diet--a serving of Special K w/ skim milk in the morning, 1/2 c. cottage cheese and canned fruit or half a grapefruit for lunch, and Special K for dinner. I lost about 20lbs in a month and she felt victorious. She quickly grew bored and I was back to being on my own and being yelled at for being fat.
The constant harping at me about my weight and total lack of any healthy foods in the house made me feel like, "Fuck it, I'm worthless." so I piled on the pounds and comfort ate because the only thing that comforted me or made me feel good was food. There was also some skeeziness from certain family members that I won't go into and I felt safe being bigger. I felt stronger being bigger. I felt like I was wearing a suit of armor made of fat and that it protected me. I liked the fat that I had because as long as I wore it, nobody wanted to mess with me.
Eventually, I became suicidal in the middle of high school (I'd mentioned this to NMom and was told to "Get over yourself!"...thanks, Ma). The constant verbal and emotional abuse from my NMom and physical abuse from my GCBrother made me want to disappear. I stopped eating. I would chew food for the taste and then spit it out in the trash. I sustained myself on a few crackers and maybe an apple a day. I ran every day, hoping my heart would stop and that everything would just end. As I lost weight, I became more socially acceptable for my NMom and she praised me. Even while I was passing out in the shower, in my room, down the stairs, she praised the weight loss. Then she decided that I was too thin, I was threatening as a woman, and she said I was so thin I was ugly, like an alien. I was a size 6 and built like a 90's era Victoria's Secret model and had had strangers come up to me and say that I looked like a VS model. I felt terrible, but I looked amazing. In any case, with the help of my SO, who'd liked me at my heaviest, I started to fix my relationship with my body. I gained weight--more than I'd have liked, but I'm finally happy with me. I have ownership of my body and fuck anybody who doesn't like it.