I agree, but what I find confusing is that I don't see why we should need an obligation, moral or otherwise, to be healthy. The motivation should be that is feels so much better to be fit and healthy. It's like saying you have an obligation to not throw yourself off a cliff. I mean ... I don't need much encouragement to not do that. That's the default. Health is the same. I am thin because that's the default and that is what is naturally best.