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.

摘要
本研究旨在评估自我报告数据在计算体重指数（Body Mass Index，简称BMI）及营养状况中的应用价值。本研究针对1000名学生开展了一项横断面定量研究，同时收集了经培训的评估者实测的受试者体重、身高数据，以及受试者自我报告的体重、身高数据。
结果显示，受试者自我报告的体重较实测值平均低0.3kg，自我报告的身高较实测值平均高1.0cm，由此导致通过自我报告数据计算得到的BMI显著低于实测BMI（p<0.001；r=0.34）。
与实测BMI的一致性分析结果表明，自我报告BMI具有极高的可靠性。以实测BMI为基准开展营养状况评估时，营养正常个体占比升高2.3%，肥胖个体占比降低3.2%，其中男性群体的肥胖个体占比降幅更为显著，达6.1%。采用自我报告BMI进行评估时，共有14.5%的受试者出现了营养状况分类结果的变动。
综上，自我报告BMI与实测BMI之间具有良好的一致性，但研究结果提示，单独使用自我报告BMI或将其作为连续变量进行分析时需谨慎；采用分类后的BMI数据开展营养状况分类似乎更为合适。