Oh OP my husband is the same and I hate it.
He is so good looking and it's all lost in fat around his face - he's rubbish at shaving now and got a huge bushy beard which is not nice and his stomach is MASSIVE - like a great big beach ball - he's got piles of fat around his back too.
He's got problems with a herniated disc and this is exacerbated by the weight at the front.
About 2 years ago he used a tracker app to monitor his food intake and lost about 1.4 stone - he was starting to look really good again and I didn't hear him complaining about his back - but now right back up to where he was 2 years ago - huge.
I feel a lack of respect for him just like you do for your husband - they know what's causing this and just can't stop putting things in their mouth - that's where the lack of self respect is.
It's causing problems in our sex life too - I have to hold his stomach out of the way when we have sex and he had some erectile dysfunction last week - he said it was due to the painkillers he had taken for his back - but it's all related.
I've got no answers for you - I agree with other posters who say he's got to want it - mine doesn't. He just doesn't find anything more important than what he's eating and drinking at the moment.
I try to encourage too but it doesn't work - he's lazy with general maintenance round the house and garden - never hoovers or washes floors or bathrooms and doesn't do any of the regular gardening such as moving the lawn or cutting the hedge.
He does all the shopping and cooking and doesn't buy "junk" as such but likes real calorific things like potato dauphenouis and duck breast and venison stake and he adds oil to EVERYTHING - sour cream to fajitas and cheese on lots of things - just overeating generally and then larger / wine /vodka to add to the mix.
He's about 4 stone heavier than when we met and just looks totally different - I'm really sad about it too :(