I think it's a good idea. I don't think people realise just how much fat and sugar is in those mega sized drinks. Nobody needs a litre of coke with their meal, in fact I'd say most people don't want that much, but people buy them and drink them because they think it's a good deal. I'd say the majority of people who buy these drinks don't do it consciously, they do it because when they order a meal from McDonalds, the staff say "would you like a large for only $1 extra?" and they oblige. The portion sizes in the USA are insane.