Although there are a number of factors associated with diabetes and obesity, ranging from genetics to individual behaviors, the composition and structure of neighborhoods and social environments have been increasingly implicated as impediments to maintaining a healthy lifestyle. Both physical activity and healthy eating are important for preventing and reducing obesity and diabetes.

California has enacted reforms to encourage healthy eating, including requiring chain restaurants to display calorie information and prohibiting the sale of soda and other sweetened beverages on K? school campuses.

However, the study authors conclude that more needs to be done to promote environments that promote regular exercise and healthy eating.

Other study findings:

Hardest-hit counties

Obesity prevalence was highest in Imperial (39.6 percent), Merced (34.3 percent) and Tulare (31.1 percent) counties, while diabetes prevalence was highest in Tulare (12.1 percent) and Fresno (10.9 percent). Regionally, the San Joaquin Valley had the highest prevalence of both obesity (30.0 percent) and diabetes (9.4 percent). Los Angeles County, due to the size of its population, had by far the most obese residents (1.7 million) and the most residents diagnosed with diabetes (642,000).

Low-income adults at risk

Adults living below the poverty line had a significantly higher prevalence of obesity (27.7 percent) than higher-income adults (19.6 percent). Similarly, diabetes was more prevalent among the poorest adults - those living below 200 percent of the federal poverty level.

Education a factor

The prevalence of obesity was nearly twice as high among adults with no more than an eighth-grade education (30.3 percent) as among those who graduated from college (14.9 percent). Diabetes prevalence was three times as high among adults with no high school education (14.8 percent) as among those who graduated from college (5.1 percent).

The study is based on data from the 2001, 2003, 2005 and 2007 California Health Interview Survey (CHIS), the nation's largest state health survey.

Source: University of California - Los Angeles