You know what's funny? Before the 1940s, we didn't really have a problem with obesity, heart disease, diabetes, non-alcoholic fatty liver disease, PCOS, or any number of other diseases tied to diet. The groups that had problems had a diet much like we do today (high in flour and sugar, low in fat) except with less protein.

I'm not saying we can't improve on what was "known", and we can certainly understand the methods of actions. They also got a lot wrong. I'm just looking for a little humility in nutrition science.

So, what did they get wrong?

  Smoking is ok (or, maybe even healthy).
  Exercise is unhealthy[1].
  Making dinner after wiping away black plague puss w/o washing hands is OK.

1. Ironically, the alternative of too much exercise may be unhealthy as well.