My DP is almost 22 stone and wants to lose weight. He can't/won't exercise due to an old sports injury but has a fairly active job. He's downloaded MyFitnessPal and logs his food, but as far as I know in 6 weeks hasn't lost anything (he lost 2lb then put 2lb back on). My belief is he's not being honest about his food intake/portion sizes.
Last weekend when we went out I really struggled to deal with his obsession with food. He had a huge lunch (full rack of ribs with sides etc), because he said if he ate now he would eat 'light' for dinner. So on the way home we bought a sandwich meal deal which I knew I probably wouldn't even eat. Within hours he was talking about ordering pizza or fried chicken, and although I didn't want to eat eventually we ended up at an Italian place.
What shocked me though was that I was on 1/4 of the way through my pizza, and he had already inhaled his. He barely even chewed it. His only comment was, 'oh, I must have been hungry'.
On the way home he suggested getting ice cream and snacks for later. I was uncomfortably full and told him so and he eventually dropped it. But I know that if he'd been alone he would have eaten more. It actually put me off seeing him for a few days because I ended up overeating myself and I felt unwell afterwards.
Today I suggested we go to the Harvester, have a huge salad while we wait for our food, and then hopefully he wouldn't eat so much of his main meal. i.e. fill up on healthier stuff first.
I went to the salad bar and had a pretty standard cucumber, tomatoes, sweetcorn, olives, onions, lettuce, croutons, bit of coleslaw etc.
He came back with a bowlful of noodles and pasta 
. No salad. There was not a single thing in his bowl that had ever been living!
This is coming between us. It's him that wants to lose weight, as in it wasn't my idea and I'm not pushing him, but I can see he's making all the wrong choices. I actually find a bigger guy attractive, but I am very concerned about the impact this is having on his health. Plus having seen the way he's blindly obsessed with food and yet when he gets it barely even chews it before it's gone makes me think that there's more to this than just saying 'eat healthy'.
Does anyone have any advice as to how I can help him? I'm out of ideas 
Do I just leave him to it (he's an adult that knows about nutrition after all) and just not eat out with him anymore? I don't know how many more times I can sit and watch someone inhale a full rack of ribs in literally 5 minutes.