The report by the Centers for Disease Control and Prevention in Atlanta says states can do more to improve food access, regulations and policies to promote healthy eating and fight childhood obesity.
Thirty-two states and the District of Columbia scored at or below the national average on an index that calculates the number of food retailers selling healthy foods, the report says.
Dr. William Dietz of the CDC says the Modified Retail Food Environment Index is a measure of the proportion of food retailers that typically sell healthy foods within a state. Scores can range from 0 -- no food retailers typically selling healthy food -- to 100 -- only food retailers that typically sell healthy food.
Nationally, the average mRFEI score was 10. State-by-state scores ranged from highs of 16 in Montana and 15 in Maine to lows of 5 in Rhode Island and 4 in the District of Columbia.
Forty-nine percent of middle and high schools permitted less healthy foods such as candy, soft drinks and fast-food restaurants to be advertised to students on school grounds. In Ohio, nearly 70 percent of middle and high schools allowed such advertising versus 24 percent in New York.
"Childhood obesity has tripled over the past 30 years," Dr. Thomas Frieden, director of the CDC, says in a statement. "This report underscores the need to make healthier choices easier for kids and more accessible and affordable for parents."