Objectives: To project prevalence of adults obesity to 2012 by age-groups and social class, by extrapolating the prevalence trends from 1993 to 2004.
Design: Repeated cross-sectional surveys 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/m2. 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 best-fitting curve (power or exponential); and extrapolation of linear trend based on 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 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; 34.8) in men and 31.0% (95%CI: 29.0; 33.1) in women. The projected 2012 prevalence for adults in manual social classes is higher (34%) than adults in non-manual social classes (29%).
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 34% are from manual social class 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.