I recently found Dr John McDougal on YouTube who has the solution to obesity based on history, current societies, and science. There seem to be two rules: 1) Base your diet around starchy vegetables (potato, wheat, oats, rice, corn, etc). 2) avoid fats, especially refined fats, and protein. 3) salt and sugar are not health foods, but are allowed to help you stick with rules 1 and 2. People, and societies, that eat like this are thin and healthy.
As someone who works out daily; the point at which I was in the best shape of my life was when I was consuming large amounts of fats. Peanut butter, olive oil, etc. I also find it really really hard to believe that protein would cause obesity; I've heard the exact opposite.
* so long as they are biologically adapted to such a diet.
People have been posting similar studies of Indian and Asian countries, basing their recommendations for everyone off that subset of the population, and then completely discount that of traditional European, African, and American diets.
