My inlaws have recently started a diet and are full of the joys of how they can eat so much and they've already noticed their clothes are looser etc etc.
My DH is also overweight. I'm not.
My inlaws have repeatedly said to me that DH ought to try the diet, why don't I cook him this recipe, he needs to lose weight for health reasons.
Until I snapped at them 'I cook healthy meals, but if he chooses to fill up on crap after dinner then that's his choice and I can't stop him'
So AIBU to think it's not my responsibility for him to lose weight and if he wants to, he needs to a least add in a smidgen of willpower!