This thread is fascinating as it highlights the double standards we adopt, both on Mumsnet (eg different advice offered depending on whether it is sought by a man or a woman), or in society in general.
For example, some posters have made the point that for someone who is obese, their relationship with food is not dissimilar to someone's relationship to alcohol, drugs, or gambling if they are an addict. I agree with this, and I think what and how we choose to eat is a very complex issue.
However, what differs, is that if a poster comes on here describing her relationship with an alcoholic partner (I'm using this example as there are a few threads on this running at the moment), then the advice is quite firmly to leave. In the case of the OP, living with someone who has changed significantly over the years, and which is impacting negatively on the family (eg example to children, quality of relationship, life expectancy etc), she is lambasted by many posters for wanting this to change.
I don't know the rights and wrongs of this, but let's stop pretending that it is wrong to maintain the same level of attraction to people if they change significantly. For some people,this is fine, and I am talking about attraction, not love here, but let's be realistic.
OP, sadly, I think that pressurising your DH will only make him more resistant. I' not sure what you do, but one thing I would do for starters is to tell him in no uncertain terms to cut out the comments about how you present yourself, if he isn't willing to have a two way discussion.