​Joelle Wolstein is a research scientist at the UCLA Center for Health Policy Research. Her recent study found the rate of obese adults in California has jumped from 19 percent in 2001 to 25 percent in 2011-2012. In this brief interview, she discusses overweight and obesity among teens, as well as hidden contributors to obesity, such as neighborhood safety.

Q: People often think obesity results primarily from poor habits. But it's more complicated, isn't it?

​Yes. Some see the increasing rates of obesity and think it's solely based on genetics or bad choices ― eating junk food instead of healthier foods and playing video games instead of getting exercise. But being overweight or obese often results from a lack of opportunities to make better choices. The poor tend to live in neighborhoods where they feel unsafe or don't have access to safe parks, which limits their ability to exercise outdoors; they live in areas where fresh fruits and vegetables are less available or affordable, so they can’t eat the recommended amount; and they have transportation constraints and can't get to better-stocked grocery stores where there are healthier options, so they eat the less healthy foods available in their neighborhoods. These and many other social and environmental problems also factor into why Californians are becoming more obese.

Q: The adult obesity rate must have gotten better in some areas of the state between 2001 and 2012?

​The rate went down in four counties, San Francisco, San Mateo, San Luis Obispo and Yolo, but these decreases were not statistically significant, meaning the differences we found may not be reliable estimates of what occurred in those counties. Unfortunately, we also found that rates went up significantly in 16 counties and in 6 of those counties the rates increased by at least 10 percentage points. Tehama/Glenn/Colusa counties had the largest increase of 14 percentage points.

Q: You focused more on adult obesity than adolescent obesity ― are we doing better in that area?

​Not really. Seventeen percent of teens were obese and 16 percent were overweight, statewide. It’s encouraging that these figures have not changed drastically in California since 2001 but teen overweight and obesity is still high. Additionally, there is a great deal of variation by county: from 13.7 percent of teens in Marin County to 48.7 percent in Solano County. Studies have found that overweight or obese teens often grow up to be obese as adults, so it is important to instill healthy habits from a young age. We need to address the sources of these disparities and invest in the health of our youth so they have the opportunity to become healthier adults.