I stumbled on a great interview with cardiothoracic surgeon, Dr. Steven Gundry, on Jimmy Moore's Livin' La Vida Low-Carb Show. (Or, cut and paste: http://www.thelivinlowcarbshow.com/dr-steven-gundry-part-1-episode-179/)
Dr. Gundry has some fun ways of looking at eating and health. I found his comments on the activation of genes (discussed at a very light, non-scientific level) useful. He argues that when humans consume sugar-containing foods, the signal received by the body is that winter is approaching and it's time to build up fat stores in anticipation of the food shortages of cold weather. He finds parallels for this phenomenon in other species. Of course, for humans, winter (in the form of extended calorie deprivation) never comes. In fact, you might argue that, given our excessive reliance on grains, corn, and sugars, that we are, in effect, always in anticipation of a winter that never comes.
I've not read Dr. Gundry's books, but I found this light interview a lot of fun.