Redline,
Think about the "Big 3" that we were supposed to be scared of - salt, fat, and cholesterol. The government was wrong on all 3. Dead wrong. I don't think they wanted to be wrong. It had to do with cronyism research, but it also had to do with the nanny state. They knew that salt wasn't a problem, imo, but because it was typically found in processed and/or fatty foods, they invented a "one size fits all" paradigm and told us to avoid salt rather than think for ourselves.
With fat, again, a mixture of incomplete research (i.e. trans fat) and poor common sense. The sheeple can't think for themselves, so we'll just tell them to avoid all fat.
With cholesterol, poor understanding of the difference between LDL and HDL cholesterol.
What is the new "Big 3?" I'd say Sugar, Sedentary, Smoking. Maybe Sweeteners. Even with sweeteners, it's kind of a nanny state. It's not that the sweeteners themselves are harmful; it's likely moreso that they trigger cravings while providing no sustenance. If you had to eat a giant apple every time you had a diet Coke, it would probably work better.