You're in the right path then. Sounds like someone is possibly a little insecure. Maybe a good time for some gentle discussion.
I was dating a woman for 6 months. She'd joke about her inner fat girl and tell me I was too skinny. I am sitting about 25% body fat which is barely below overweight. She got offended when I point blank told her I didn't spend 5 years reclaiming my health to start ignoring it for a relationship or to stay with someone who doesn't support and appreciate my self improvements.
A month later I had to move on because she never accepted how I like to cook. She even admitted she really wanted to try it as it looked delish, but still refused. I reached a point my where health and weight were trending back. I literally would have healthy meals to prepare for us and she insisted on fast food cuz it was easier.
Ultimately I decided I didn't want to make a life with someone who was headed for long term age related health issues. I can understand that isn't always predictable and uncontrollable health events are one thing, but habits which I know end up as type 2 diabetes and other poor health do not support my futures goals of travel and adventure. I felt like she wouldn't put in the effort to keep herself reasonably healthy.
Marriage is different, but you may want to keep in mind she's now got to adjust to a changed man. That can be a scary thought if she isn't reassured by the new you on why you've changed. Older men in control of themselves are rare enough to receive attention from women of all types. I would make certain she understands how this change impacts my feelings for her. And it is entirely possible you many decide you have a new view now about what type of health you want in a mate.