Validity of self-reported body mass and height: relation with sex, age, physical activity, and cardiometabolic risk...

To evaluate the validity of self-reported body mass and height measurements in adolescents, adults and older adults according to sex, age, leisure-time physical activity level, nutritional status, and cardiometabolic risk factors.

The study included 856 subjects, aged 12 years or older, who participated in the São Paulo Health Survey (ISA-2015) and who had their body mass and height measured and self-reported. Based on the Body Mass Index (BMI), a classification of nutritional status was made according to standardized criteria for each phase of life. The validation of self-reported data was examined by the Intraclass Correlation Coefficient, Bland-Altman and paired T-Test. Linear regression models were used to estimate the calibration coefficients, and sensitivity and specificity tests were performed.

Self-reported body mass and height values tend to be very similar to measured values, with a few exceptions. For the adolescents, an underestimation of height was noted, while for the older adults, an overestimation. There was a consistent underestimation of self-reported body mass among women, and an overestimation of BMI among men who practiced less than 150 minutes of physical activity per week during leisure time. The calibration process of self-reported measures made them more consistent with the values measured, increasing the sensitivity in the classification of nutritional status among women and the specificity among men.

Self-reported measures of height, body mass and BMI provided valid and reliable measures, presenting a substantial improvement after calibration.