Associations between body mass index and health-related quality of life among Australian adults

To assess the relationship between body mass index (BMI) and health-related quality of life (HQoL), as measured by the Short Form Health Survey (SF-36) within a sample with broad population coverage. Survey data incorporating the SF-36 questionnaire, height and weight were obtained from a nationally representative sample of 9,771 Australians aged 21 or older (4,649 men and 5,122 women). Linear multiple regression methods were employed to estimate the magnitude of association between BMI classes and HQoL variables, adjusting for disability and other covariates. Less than 1% of men and just 3.5% of women were classified as underweight while 52.2% of women and 65.9% of men were classified as overweight or obese. For all SF-36 health dimensions, people with BMI scores in the healthy range reported, on average, higher health-related HQoL scores than underweight and obese people, and HQoL scores decreased with the degree of obesity. Although overweight and obesity were associated with decreasing levels of both physical and emotional well-being, the deterioration in health status was significantly more evident in the physical than in the mental, social or emotional dimensions. Low and high BMIs were associated with decreasing levels of both physical and emotional well-being, but the deterioration in health status was more consistent in the physical than in other dimensions.