Obesity has risen for decades and social scientists and government officials have scrambled to link cause and correlation, proposing everything from low income to public parks to a thrifty phenotype hypothesis, which says that poor people are biologically unfit to not be poor.

Income may be less of a factor, according to a report by The Centers for Disease Control and Prevention (CDC). Despite record-level food stamp usage, chronic under-employment and earnings increases below the rate of inflation, 19 states saw obesity among low-income preschoolers decline between 2008 and 2011. 

The Vital Signs report found that Florida, Georgia, Missouri, New Jersey, South Dakota, and the U.S. Virgin Islands saw at least a percentage point decrease in their rate of obesity. Twenty states and Puerto Rico held steady at their current rate. Obesity rates increased slightly in three states. 

Previous research determined that about one in eight preschoolers is obese in the United States and population analyses show that children are five times more likely to be overweight or obese as an adult if they are overweight or obese between the ages of three and five years.

For the Vital Signs report, CDC researchers analyzed measured weight and height for nearly 12 million children aged two to four years who participate in federally funded maternal- and child-nutrition programs. Forty states and the District of Columbia and two U.S. territories (U.S. Virgin Islands and Puerto Rico) were included in the report. The data come from the Pediatric Nutrition Surveillance System.

CDC is encouraging state and local officials to step up efforts to drive down rates of childhood obesity. Business leaders, childcare providers, healthcare providers, communities, and families are some of the groups that influence nutrition and physical activity in the places where young children live, learn, and play. State and local officials can assist these groups by:

• Making it easier for families to buy healthy, affordable foods and beverages in their neighborhoods.
• Helping provide access to safe, free drinking water in places such as community parks, recreation areas, child care centers, and schools.
• Helping local schools open gyms, playgrounds, and sports fields during non-school hours so children can play safely after school, on weekends, and over the summer.
• Helping child care providers adopt best practices for improving nutrition and physical activity and for limiting computer and television time.
• Creating partnerships with civic leaders, child care providers, and others to make community changes that promote healthy eating and active living.

“While the changes are small, for the first time in a generation they are going in the right direction. Obesity in early childhood increases the risk of serious health problems for life,” said CDC Director, Tom Frieden, M.D., M.P.H.

First Lady Michelle Obama was quick to credit her Let's Move! Child Care Initiative, which promotes putting chefs in schools and more labels on food. “Today’s announcement reaffirms my belief that together, we are making a real difference in helping kids across the country get a healthier start to life. We know how essential it is to set our youngest children on a path towards a lifetime of healthy eating and physical activity, and more than 10,000 childcare programs participating in the Let’s Move! Child Care initiative are doing vitally important work on this front. Yet, while this announcement reflects important progress, we also know that there is tremendous work still to be done to support healthy futures for all our children.”