However, I think the Paleo Diet folks have the grains thing partially right. I was listening to an interview of Gary Taubes (author of Why We Get Fat) recently and he theorized that the overabundance of simple carbs such as sugar, HF corn syrup, and white flour is is the leading cause of weight gain and retention.

He thinks, similarly to the Paleos, that our ancestors would not have had such ready access to sugar and therefore we evolved to produce an insulin reaction to simple carbs, which in turn tells to body to start storing it as fat, presumably because these sources would help our ancestors in lean times. He also noted that other foods, even ones with sugars such as fruits and vegetables do not illicit the same reaction in the body.

His conclusion was to almost totally eliminate carbs from his diet, but it seems more sensible to avoid refined sugars and simple carbs as much as can be tolerated and to not worry as much about the complex carbs. This would seem to fall in line with those that give up soda and manage to loose significant weight.

I also believe you are right about the Paleos error in making meat the centerpiece of diet. They have been criticized for not looking particularly closely at the actual diet of Paleolithic Man and this is one area that fits that criticism because, with the exception of arctic dwellers that subsist almost entirely on meat, meat, especially big game, was not the center of our ancestors’ diet. Fish was a much more common protein source and nuts would have supplemented.

So, looking at “the Land of Sushi,” though white rice is somewhat refined and less nutritious than brown rice it is much less refined than sugar and white flour and having fish as the central protein source is also healthier and better for the environment. So the Japanese really do eat closer to a true Paleo diet and are healthier.