ugh, who knows what kind of rabbit hole this may send your thread down, but what the hell...
Have you ever heard of the paleo diet? Long and short it's a low carb diet. It focuses on eliminating grains, dairy, and legumes. The gist of it is simple- we as homosapiens throughout evolution (until the point of the agricultural revolution at least) had a very simple diet which consist of meats, fats, seasonal fruits, veggies, some limited root plants (potato for example) and nuts. Hence our bodies have evolved to run on this fuel.
You've maybe heard the term "caveman diet". I can't possibly give proper justice to the health benefits of this diet because I'm far from an expert. Consider checking out The Paleo Solution
. The author also has a web site with some helpful info at http://robbwolf.com/.