I'm sure we'll discover what diets work for what people and why. Essentially, we're trying to hack a way to do something unnatural in a sustainable manner, because we have all the sugar, fat and salt we want readily available to us and gorging on them the way our genes tell us to (for what were excellent reasons for most of the last million years) will be bad for us. This is a much better problem to have, but of course it's still a problem: how to cope with abundance.