ESTIMATION OF BODY MASS INDEX FROM SELF-REPORTED MEASURES: WHAT IS THE VALIDITY?

ABSTRACT The aim of this study was to evaluate the use of self-reported measures for calculating body mass index (BMI) and nutritional status. A cross-sectional quantitative study was conducted on 1,000 students. Body weight and height were measured by a trained evaluator and were obtained by self-report of the participants. There was a trend towards underestimation of body weight by 0.3 kg and overestimation of height by 1.0 cm, which resulted in lower self-reported BMI compared to measured BMI (p <0.001; r = 0.34). Analysis of agreement with measured BMI showed very high reliability of self-reported BMI. The evaluation of nutritional status based on measured BMI resulted in an increase in the percentage of eutrophic individuals (+2.3%) and a decrease in obese individuals (-3.2%). This decrease was greater among men (-6.1%). A change in nutritional status classification occurred in 14.5% of the participants when evaluated by self-reported BMI. In conclusion, there is good agreement between self-reported and measured BMI, but the results suggest caution in the use of self-reported BMI alone or as a continuous variable. Categorized information seems to be more appropriate for the classification of nutritional status.