Overall, 34 per cent of adult Americans have the problem, and it's present even in 18 per cent of those aged from 20 to 39 years.
These figures, based on statistics for 2012, show a small increase of two per cent over the previous overview, which was conducted in 2004. However, there has been a drop of 3 per cent among adult American women.
The researchers reckon the rate is stabilising, mainly because people are becoming more aware of the dangers of obesity and poor diet, say researchers from the National Health and Nutrition Examination Survey.
(Source: JAMA, 2015; 313(19): 1973)