So what's driving Oregon's obesity decline? The AP alternately pins responsibility on Oregon's breasts, nutritional labeling and racial demographics:
Black and Hispanic young people in the study were twice as likely as whites to be overweight or obese, even when the researchers took into account other risk factors like inactivity and poverty. Oregon is 90 percent white. It also has a high rate of breast-feeding, and some research suggests that protects against obesity.
Oregon law sets nutrition standards in schools and requires chain restaurants to provide nutritional information on request. Those steps, taken recently, wouldn't have shown up in the new study's results, but may reflect Oregon's inherent interest in health.
But then the AP article also notes that kids who live in neighborhoods with "poor housing and no access to sidewalks, parks and recreation centers had 20 to 60 percent higher odds of being obese or overweight." So maybe Oregon's (or at least Portland's) prevalence of parks and sidewalks (west of 82nd Ave) help out our obesity levels?