From an ecological perspective, obesity can be understood as an adaptation to a complex modern society.(1) Healthy lifestyle recommendations on how much physical activity to get and what and how much to eat continue to be updated and refined, most recently by the US Department of Health and Human Services and the Department of Agriculture in the Dietary Guidelines for Americans 2005.(2) These new insights and interpretations build on fundamental principles and recommendations that have been in place for many years,(3) yet sedentary behavior and overeating are more pervasive than ever. We see these problems firsthand every day, both as clinicians and as concerned citizens.