I'll likely get blasted for this, but oh well. What I would want to know is if your husband and you has ever had a conversation, prior to the marriage, about what is expected in terms of the person's body weight, size, activity level, etc.? Not sure where you are at, but in the US, 2/3rds of the population is overweight, with around 1/3rd actually being obese. It is a real health crisis that we are facing. Childhood weight issues are a new thing, as it seems today's kids don't eat great and if they aren't active in sports, do a lot of just lounging around. This could have a serious impact on the US in the future.

So, is your husband in shape? Is he very fit or just average or above average? Are you two active outside of working out: Rec sports, hiking, swimming, etc.? If so, it is possible he fears that your activity level will dwindle but your eating habits won't. It doesn't take much at all for a person to put on 20 pounds, and then it is 40 pounds, and for some, they just can't stop and they are your height and approaching or over 300 pounds. The people who go to the extreme are on that show "My 600 pounds life." A partner who puts on significant weight in a relationship might causes intimacy issues, recreational issues (can't go hiking anymore, can't go swimming, etc.) with the spouse, and even healthcare issues.

If he is concerned, he should let you know what he expects from you and you from him. It should be clearly understood that if either of you change, it could be grounds for divorce. People will say that is wrong, but at the same time, people usually want the person they dated to stay the same, not change. Just because there is a marriage or kids doesn't mean a person should be given a pass on their weight. I'd tell your husband to stop, but if he doesn't, then it might be on you to decide what to do: Stay and deal with it or leave.