Hi, what you’re describing is an abusive person. You need to leave this situation immediately. People like this do not change, it is over. If you’re married see a divorce lawyer while not changing any behavior that would tip your husband off. If you’re dependent on him financially or in some other way make a long term plan with a divorce attorney to get yourself in a good place to leave. There are so so many healthy and well adjusted fish in the sea. So many. If it were standard marital problems then that would be one thing, but leaving you for gaining weight and forcing you to eat bite after bite? Leave. Don’t just say no. Leave.
I know you’re seeking IF advice, not relationship advice, but everyone here is right - your partner’s behavior is troubling and the dynamic does not appear healthy. First of all, if he’s hungry at night, why are you the one preparing him a snack? A grown man can make his own food. But then to demand that you sit and eat with him when you’ve expressed you don’t want to? That is just nutso. On top of, of course, how disrespectful it was for him to claim your weight gain was an issue for him - all the worse given that he’s also gained weight AND is not supportive of your efforts to improve your health. I am sorry to say it but you will be way better off without this guy, and I think you know it yourself.
So many red flags here.. I would have a talk about our health and that you need him to support you. This doesn’t sound like he is worried about you but being selfish. Is this a person you want to be with long term? Sending positive thoughts, this sounds hard.