I think you should just talk to him. He probably feels insecure and the food thing. ..well I have lived with someone who "forced" their diet on me and it is surprising how bitter you become. Even though I obviously cooked my own meals and that wasn't the issue, it's like I felt judged. Even though from a rational standpoint I understood that this wasn't even about me but it did reveal my own failures about my own food choices and my lack of self-control.
There are probably a lot of issues going on here that have nothing to do with your weight loss. It more about insecurity over the possibility of losing you and the self-awareness that he may be failing you.
He feels threatened by the weight loss and when people feel threatened they are at their worst even with the people they love (actually they are probably worse because a stranger you tell you where to stuff it).
I think you should both comfort him BUT also tell him is lack of support is not okay. That being healthy is for both of your happiness and he needs to get behind that.