The researcher said that the decline was largely due to more people reporting a normal weight – 36.1% in 2011, compared to 35.4% in 2010 – while the number of overweight Americans showed little change, suggesting an overall downward shift in body weights.
Although the 0.5% move in the obesity rate is a slight change, the result is significant because of the enormous cost to society of obesity-related illness and disease, Gallup said.
“The slight drop in America's obesity rate is a positive reversal of what was previously a negative trend. The cost of obesity is so high that even this small improvement has the potential to save the American economy a significant amount of money,” its report said. “…But with more than one in four adults still obese, the nation has a long way to go to achieve lasting change.”
Gallup said its own research has found obesity and associated health issues to cost about $153bn each year, but figures vary widely. A December 2010 estimate from the Society of Actuaries suggested the total cost the US economy could be as high as $270bn a year.
Gallup’s findings are based on data from its Gallup-Healthways Well-Being Index, which has included self-reported information on body weight for a random sample of American adults since 2008. The 2011 poll included data from more than 335,000 US adults from all 50 states and the District of Columbia.
Whether a person was considered obese, overweight or normal weight was determined according to body mass index (BMI), a ratio of height to weight.
Demographic groups most prone to obesity were blacks, low-income Americans and those aged 45-64, the study found.