Rising Obesity

Very cool graphic based on the CDC's Behavioral Risk Factor Surveillance System, a telephone survey that tracks health conditions. Amazingly quick growth in obesity (which I think is BMI>30 but I could be wrong - it's either 30 or 25) since 1985. What's causing this? Is it a cohort effect? The unconditional changes don't control for anything except state and year, so you can't see whether these are growths in BMI within a given cohort, or if it's an increase in BMI among the younger cohort who are gradually replacing the older cohort over time. A well known paper by Glaeser, Shapiro and Cutler posits that the growth in obesity is being driven by falling food prices and food preparation prices.