Yeah I think if you can you should bring it up with your son and say that them over eating is costing a lot of unecessary money, it's really not fair on you!! As well as it causing you stress seeing people over eat, that would effect me a lot too. Sometimes my step dad has huge meals and it makes me really uncomfortable.

I wish you luck in hopefully dealing with this issue and getting people to listen to you! It's definitely wrong if it's meaning you struggle to pay doctors bills, that's really important that there is money for you to eat and go to the doctors too.