I read Gary Taubes' "Good Calories, Bad Calories" 4 months ago, which had me curious enough to experiment.
http://www.amazon.com/Good-Calories-Bad-Controversial-Scienc...The book is a meta study of the research done on the so-called metabolic disorders (obesity, diabetes, heart disease). The research doesn't talk about evolution and cavemen, but rather health markers, hormones, and metabolic processes.
I've been eating a less -ahem- tribal version of this for 4 months, and the results have been pretty remarkable (if entirely anecdotal).
I have lost a large amount of weight, my skin and hair are much improved, my digestive functions have normalized after a lifetime of trouble, and I'm no longer tired all the time.
I haven't been sick since I started, but 4 months isn't exactly long enough to suggest anything in that respect.
What I do differently from the tribal version in the article is
1) I don't exercise (yeah, I know, evil, but I just don't feel like it yet)
2) I eat tomatoes and cheese and cream
3) I don't fast; I eat whenever I'm hungry. Interestingly, I'm only hungry about twice a day now, rather than 5 or 6 times a day which was the norm for me before I started this experiment
4) I'm super relaxed (pragmatic?) about the whole thing. I haven't seen the light or anything like that, I've simply had some really good results with very little effort.
There is a blog at http://www.marksdailyapple.com which has plenty of interesting articles, as well, but the Gary Taubes book is the closest thing I've found to proven health benefits.