title: Validity of self-reported weight--a study of urban Brazilian adults.
abstract: In order to evaluate the validity of self-reported weight for use in obesity prevalence surveys, self-reported weight was compared to measured weight for 659 adults living in the Porto Alegre county, RS Brazil in 1986-87, both weights being obtained by a technician in the individual's home on the same visit. The mean difference between self-reported and measured weight was small (-0.06 +/- 3.16 kg; mean +/- standard deviation), and the correlation between reported and measured weight was high (r = 0.97). Sixty-two percent of participants reported their weight with an error of < 2 kg, 87% with an error of < 4 kg, and 95% with an error of < 6 kg. Underweight individuals overestimated their weight, while obese individuals underestimated theirs (p < 0.05). Men tended to overestimate their weight and women underestimate theirs, this difference between sexes being statistically significant (p = 0.04). The overall prevalence of underweight (body mass index < 20) by reported weight was 11%, by measured weight 13%; the overall prevalence of obesity (body mass index > or = 30) by reported weight was 10%, by measured weight 11%. Thus, the validity of reported weight is acceptable for surveys of the prevalence of ponderosity in similar settings.
authors.affiliation: Department of Social Medicine of the Faculty of Medicine (UFRG) Porto Alegre, RS, Brazil.
authors.forename: M I
authors.initials: MI
authors.lastname: Schmidt
authors.forename: B B
authors.initials: BB
authors.lastname: Duncan
authors.forename: M
authors.initials: M
authors.lastname: Tavares
authors.forename: C A
authors.initials: CA
authors.lastname: Polanczyk
authors.forename: L
authors.initials: L
authors.lastname: Pellanda
authors.forename: P M
authors.initials: PM
authors.lastname: Zimmer
mesh_terms: D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D001835:Body Weight; D001938:Brazil / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology*; D015995:Prevalence; D015203:Reproducibility of Results; D014505:Urban Population