I'm going to go out on a limb here and claim that obesity is an epidemic because of the misguided anti-fat crusade driven by well-meaning but naive people who (still!) believe that "eat fat get fat". You can walk down the ice cream isle and see countless sorbets advertising "fat free!" as if it's healthy.

We are at the tail of a huge shift to a carbohydrate-rich diet, and refined sugars are only part of the problem. Your body converts bread and starch to glucose almost as quickly.

The fearmongering about social media sounds a bit like the anti-fat crusade to me. The evidence is thin yet it makes people incredibly loud and angry. And remember one of the first rules of statistics, correlation is not causality. I don't need to quote the relevant xkcd number to this audience.