You might be right -- maybe no amount of research and knowledge can help this problem. Still, since this problem is costing us trillions, I don't mind a few million here and there for research -- maybe they'll find something that helps at least a few people.
In a free society we should not be paying for the eating habits of other people. So, you see, the "few million here and there" should be moot as the "obesity epidemic" should be costing society nothing. It's the obese that should be paying for their obesity.