The Bay Area has the lowest prevalence of adult obesity in California. That’s according to a new report by health researchers at UCLA who looked at survey statistics from three years ago.

Bay Area counties with the largest populations of low income, non-white and non-Asian residents, had the highest rates of obesity. Napa and Sonoma counties, which both have large migrant worker populations also had high obesity rates. About 28 percent of adults in both of those counties are considered obese.

San Francisco and Marin counties however, which are the region’s two wealthiest, had the lowest obesity rates, close to 12 percent and 13 percent respectively.

The report, by the UCLA Center for Health Policy Research, was based on information collected in the California Healthy Interview Survey in 2007.