Twelve-year weight change, waist circumference change and incident obesity: The Australian diabetes, obesity and lifestyle study

Objective This study aimed to describe the changes in weight and waist circumference (WC), examine the incidence of obesity as defined by body mass index (BMI) and WC, and describe the changes in the prevalence of obesity over 12 years. Methods In 1999/2000, 11,247 adults aged 25 years were recruited from 42 randomly selected areas across Australia. In total, 44.6% of eligible participants completed follow-up in 2011/12. Height, weight, and WC were measured at both surveys. Results People who were 25-34 years of age at baseline gained an average of 6.7 kg weight and 6.6 cm WC, whereas those aged 75 years lost an average of 4.5 kg and gained an average of 0.8 cm. Women had a greater increase in WC than men, but did not differ in terms of weight gain. The 12-year incidence of obesity was 15.0% when defined by BMI and 31.8% when defined by WC. According to BMI and WC combined, the percentage of the cohort that was normal weight decreased from 33 to 21% and the percentage that was obese increased from 32 to 49% between baseline and 2012. Conclusions In addition to BMI, assessment of WC should be incorporated more frequently when assessing population trends of obesity and the burden of disease associated with excess adiposity.