To investigate the accuracy of self-reported weight of overweight and obese women and characterisation of under-, correct- and over-reporters based on a number of related variables.

Weight was self-reported before entering the study. At baseline, actual weight was recorded, and demographic, health, nutritional, psychological and physical activity questionnaires were completed.

A hospital outpatient department.

Participants were 131 women aged 18–64 years with a body mass index (BMI)≥ 28 attending a Comprehensive Weight Management Programme.

The accuracy of self-reported weight was investigated for the total group, and the subjects were then categorised into three groups according to accuracy of self-reported weight (under-, correct- and over-reporters). The relationship between these accuracy groups and demographic, health, nutritional, and psychological variables and physical activity was examined, to characterise the under-, correct- and over-reporters.

Although not statistically significantly different, the total group of women tended to underestimate their weight by 0.8 (±3.6) kg. Categorisation according to the accuracy groups revealed that 29% underestimated their weight by 2 kg or more, 19% overestimated their weight by 2 kg or more, and only 52% correctly estimated their weight within 2 kg. Some trends and statistically significant differences between the accuracy groups concerning certain variables, e.g. height, age, income, education, contraceptive pill usage, smoking and food choices were evident.

Self-reported weight of a group of overweight/obese individuals may be a valid and reliable indicator of actual weight, but self-reported weight of an overweight/obese individual can not be interpreted similarly. Further research is necessary to ensure reliable characterisation of under-, over- and correct reporters.