Diet and exercise play different roles in keeping us healthy. You can be fairly overweight with a sugary diet while still being pretty active, just as you can lose weight by monitoring diet alone. Some of the problem of the changing villians is that we are still learning, and some of the problem of us not knowing more is pushback from sweetening industries.

I don't agree with all of the anti-sugar things. Probably shouldn't tax sugar itself, and in moderation it isn't a bad thing. Most folks don't have a lot of candy in their diet (because there are limits). But they do drink a good deal of sugary coffees and drinks when it would be better to eat a handful of fruit and drink some water. Most folks don't need the added sugar to feed their brain - fruit and vegetables and some grains wind up as that anyway.

It isn't sugar in and of itself that is such an issue, but that we tend to put it in everything, so our consumption is really high.

Sauces and prepackaged foods have an amazing amount of added sugar. The typical american breakfast is nearly a dessert. Cranberry juice, pushed as healthy, is generally sweetened, even if it is with concentrated fruit juice. All of these things add up especially when combined with lack of reasonable choices near you and large portion sizes. And trying to figure out what has added sugar and other such things has been proven difficult. And this is a major problem for folks trying to have some sort of balance in addition to being a problem for folks that are low-to-mid income and/or have little time to cook their own food as it gets harder to limit such things even in supposedly healthy food.