Background: This study aims to project the prevalence of adult obesity to 2012 by age groups and social class, by extrapolating the prevalence trends from 1993 to 2004. Repeated cross-sectional surveys were carried out of representative samples of the general population living in households in England conducted annually (1993 to 2004).
Methods: Participants were classified as obese if their body mass index was over 30 kg/m(2). Projections of obesity prevalence by 2012 were based on three scenarios: extrapolation of linear trend in prevalence from 1993 to 2004; acceleration (or slowing down) in rate of change based on the best fitting curve (power or exponential); and extrapolation of linear trend based on the six most recent years (1999 to 2004).
Results: The prevalence of obesity increased significantly from 1993 to 2004 from 13.6% to 24.0% among men and from 16.9% to 24.4% among women. If obesity prevalence continues to increase at the same rate, it is projected that the prevalence of obesity in 2012 will be 32.1% (95% CI 30.4 to 34.8) in men and 31.0% (95% CI 29.0 to 33.1) in women. The projected 2012 prevalence for adults in manual social classes is higher (43%) than for adults in non-manual social classes (35%).
Conclusion: If recent trends in adult obesity continue, about a third of all adults (almost 13 million individuals) would be obese by 2012. Of these, around 43% are from manual social classes, thereby adding to the public health burden of obesity-related illnesses. This highlights the need for public health action to halt or reverse current trends and narrow social class inequalities in health.