I would try to figure out what's stopping him from getting help; it could be that he's avoiding the issue because deep down he's ashamed of his appearance/healt

I would try to figure out what's stopping him from getting help; it could be that he's avoiding the issue because deep down he's ashamed of his appearance/health/etc and feels like he's letting everyone/himself down. If that's the case, some of your ideas might cause even more shame and push him in the opposite direction you're intending. Instead of just singling him out and isolating him as an object of shame, make healthy living an activity the whole family's involved in. Track everyone's weight loss in percentages like Biggest Loser, get everyone in the family committed to trying healthy recipes, center your get-togethers around healthy eating and family activities that everyone can enjoy. If everyone else is committed to it, he won't feel so alone and like you're trying to punish him.