In this national bestseller based on Harvard Medical School and Harvard School of Public Health research, Dr. Willett explains why the USDA guidelines--the famous food pyramid--are not only wrong but also dangerous.

The book tells the story of how we never evolved to exercise - to do voluntary physical activity for the sake of health. Using his own research and experiences throughout the world, the author recounts how and why humans evolved to walk, run, dig, and do other necessary and rewarding physical activities while avoiding needless exertion. Drawing on insights from biology and anthropology, the author suggests how we can make exercise more enjoyable, rather that shaming and blaming people for avoiding it