Objective: To investigate the extent to which people who are medically defined as overweight perceive themselves to be overweight.
Design: Secondary data analysis of the National Health Survey and the National Nutrition Survey conducted by the Australian Bureau of Statistics in 1995.
Participants: 10,652 people aged 18 years and over (5076 men, 5576 women) in a multistage cluster sample of households throughout Australia.
Main outcome measures: Body mass index (BMI) based on measured height and weight; self-reported perception of body weight (underweight, acceptable weight, or overweight).
Results: Among people with a measured BMI > or = 25, 49.3% of men (95% CI, 48.1%-50.5%) and 72.0% of women (95% CI, 70.8%-73.1%) considered themselves overweight. Among those with a measured BMI < 25, 3.4% of men (95% CI, 2.8%-4.1%) and 12.4% of women (95% CI, 11.4%-13.3%) considered themselves overweight. Older women were less likely to perceive themselves as overweight than younger women. The lowest BMI at which at least half the respondents considered themselves overweight was 26 to < 27 for women aged 18-59 years, and 28 to < 29 for older women and men.
Conclusion: For many people, particularly men and older women, the meaning of "overweight" differs from the medical definition. Clinical and public health weight reduction programs which do not take this into account are unlikely to be successful.