Obesity in South Australian adults - prevalence, projections and generational assessment over 13 years

Objectives: To examine the trend in obesity prevalence using annual representative cross-sectional samples of the South Australian population, to project the increase of obesity using current trends, and to examine the increase in prevalence by generational assessment. Methods: Face-to-face interviews of representative population samples of people aged 18 years and over living in South Australia from 1991 to 1998 and again in 2001 and 2003. Information on height and weight was provided by participants, in order to calculate body mass index (BMI) as a measure of obesity. Results: The proportion of respondents classified as obese according to their self-reported body mass index (BMI ≥30 to <35) increased significantly from 8.7% in 1991 to 14.1% in 2003 (χ² trend=79.4, p<0.001). Severe obesity (BMI ≥35) increased significantly from 2.6% in 1991 to 5.3% in 2003 (χ² trend=50.4, p<0.001). Current prevalence trends indicate that by 2013, the self-reported prevalence of obesity in South Australian adults will be 27.8%, with the prevalence in males being 26.4% and in females, 29.3%. Secular obesity trends indicate that younger birth cohorts had the greatest percentage increases. Conclusions: Obesity has increased significantly between 1991 and 2003, and is increasing fastest among younger adults. Multifactorial interventions at all levels of the population are required to prevent overweight and obesity and promote weight maintenance, weight loss and address the health burden of obesity.