I could've written this post myself, so I really sympathise with you.
No answers, unfortunately apart from resigning yourself to living a dissatisfied life as I'm doing, and living with the constant worry that he'll drop down dead. Although, it is starting to make me very resentful towards him, which means I'm snappy where I wouldn't normally be.
I love my dh and don't want to leave; I just want him to love himself and his family/me enough to actually take the time to look after himself: to lose weight and tone up and get healthy before it's too late and he has a heart attack or something.
My dh is around 5'10" and has always been solidly built at around 13½st, but as I've lost weight (11 years ago and kept it off) he has gained it and he's now almost 21st, and it's pretty much all carried around his stomach.
I find it a turn off, and (tmi, sorry!) it physically stops me from being able to orgasm as his stomach gets in the way and means we don't 'rub' together in the way I need to achieve that. I also don't find it attractive in the slightest.
I think due to how much I hated being overweight myself, that it means I struggle with how he looks even more as it reminds me too much of painful memories. I repulsed myself when I was fat and I struggle to see it in my dh without these feelings resurfacing.
I get the respect thing too. I feel disrespected and I'm struggling to give him the same respect I had previously....it's because it feels like he can't be arsed to put himself first, like he doesn't respect himself or his family enough to look after himself.
I want him to want to look good for himself and for me and our family. I want to enjoy retirement and for us to be fit and healthy so we can make the most of it.
He's had several health scares and been told he's prediabetic, has very high cholesterol and high blood pressure. Each time I thought it would be the kick he needed, but it's never lasted more than a few months.
He's been unable to get life insurance due to his weight, etc, in that the premiums are so high we can't afford them.
I've told him our sex life is suffering and that I'm scared he'll die/have a stroke, etc, but he just isn't bothered enough to do anything about it, which makes me feel he just doesn't love us enough, even though I know it isn't that easy/simple.
I feel like every day, he chooses food over our relationship and family. He comfort eats from work stress and says he'll start a diet ,etc when he's less stressed/ got more time, etc, but we both know that's never going to happen.
A few times over the last 10 years he's managed to lose a stone or 2, but he always puts it back on (& more) within 6 months. In the last 6 years he's put on about 4 stone and he's now pretty much the heaviest he's ever been.
I feel awful saying it, but I'm embarrassed when we go out and when we have people over because he'll often not wear a shirt and it looks awful, or the shirt he wears is too short so that his belly sticks out. It looks awful and makes me want to cry.
PPs are right though, in that he has to want to do it for himself and no amount of nagging will make him lose weight until he wants to.
I realised this about 6 months ago and haven't mentioned it since and despite him promising to lose weight at that time (after another frank talk), he's done nothing...he doesn't weigh himself at all, which is how I know he isn't doing anything (as he uses lbs and I use kgs), so I know if he's used the scales. He's also not lost any weight (if anything he's got bigger).
It's not what I cook as I cook healthy foods and if I'm making the dinner and dishing it out, it isn't his portion size then, but when doing food for himself he piles it on and is never full...he seems to be able to ignore it and carry on until it's all gone.
I know he eats badly/secretly outside of the house and if dinner isn't ready as soon as he gets in, even if there's only 5 mins left, he'll make himself something in the meantime and will still eat all the dinner.
He eats a lot of fruit and yogurt and salads, etc, but doesn't seem to get that you can still overeat on that (especially when adding oil/dressing, etc).
My heart is sore from worrying about it and it's really affecting my mood, etc, in general, but there's no point in speaking to him about it as he just doesn't care enough to do something about it, regardless of what it's doing to us. 😔
I even agreed to really expensive luxury (mid life crisis..think speed boat, etc) purchases in the hope it would give him the incentive to look after himself ( at the time he said it would give him focus/incentive to get fit). Needless to say, it did not work. 
We also now have a fully equipped gym at home that he never uses (all professional grade equipment too, so not cheap!).
I didn't want to buy the gym stuff and tried to put my foot down, as I said "you'll use it once or twice then get bored, same as you always have in the past" (eg, with dog, and treadmill, etc).
He promised this wouldn't be the case and he was really serious abt losing weight this time, but that it needed to be top grade stuff so it lasted. I said get a cheap one and then if you use it a lot we can always upgrade, but no it was this really expensive kit or nothing. At the end of the day, I guess I want so badly to believe him that I agreed and so we spent 1000s on gym equipment plus even more on converting shed to house them and in a year he's used it 4 times. I could cry; it's wearing me down emotionally.
We even got a dog I didn't want years ago when this 1st started to be an issue as he promised it would encourage him to get out and about, etc...that never happened and I rehomed the dog with family as I just didn't have time to walk her myself and it wasn't fair on her as she was an active dog.
I hope you have more luck 🌷🌹💐