# Accuracy of Assessing Weight Status in Adults by Structured Observation
###### Abstract  
The assessment of weight status is important in many epidemiological studies, but its direct measurement is not always possible. Self-reported weight and height are often used, although previous research reported low accuracy. This study aimed to test the ability of trained observers to accurately estimate weight status in adults using structured observation. A cross-sectional study was conducted. For each participant, height and weight were estimated in categories, and weight status was recorded using [PERSON]'s body figures, by two trained observers. Height and weight were also measured, using standardized procedures. Subjects were classified according to World Health Organization body mass index (BMI) cut-offs from objective measurements and from the BMI assigned to each body figure. Sensitivity, specificity, and likelihood ratios were calculated to assess the accuracy of estimating weight status by observation. Kappa was used to test inter-observer reliability. A total of 127 participants were assessed, 70 women and 57 men, aged between 19 and 89 years (mean \(\pm\) standard deviation: 50.3 \(\pm\) 16.3 years). Most participants were overweight or obese (64.3% women; 78.9% men). The sensitivity and specificity of overweight/obesity status identification were 72.8% and 78.4%, respectively. Observers' gender, participants' gender, and participants' age were significantly associated with the estimation of overweight/obesity. The agreement between observers was moderate for BMI estimates (\(\kappa=0.52\)) but substantial when distinguishing normal weight from overweight/obesity (\(\kappa=0.67\)). Trained observers were able to distinguish normal weight from overweight/obesity with high sensitivity and specificity, and substantial interrater reliability. This innovative methodology showed potential for improvement through enhanced training techniques. The use of structured observation may be a useful and accurate alternative to self-reported weight status assessment, whenever anthropometric measurement is not achievable.  
weight; body mass index; anthropometric measures; body size figures; overweight and obesity +
Footnote †: journal: Medical  
previous studies have shown that self-reported weight and height are often inaccurate, with individuals underestimating their weight and overestimating their height, resulting in an underestimation of BMI [4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14].  
Silhouette-based matching tests have been used to assess body image self-perception [15], since the BMI corresponding to the chosen silhouette has shown a high correlation with measured BMI in adults [16]. Specifically, assigning self-reported weight status in adults by the selection of the silhouette from the Stunkard Figure Rating Scale [17] has been reported to have a good correlation with measured BMI [18]. The validation of the Stunkard scale as an instrument to assess nutritional status was confirmed by [PERSON] et al. [19]. There is, however, a lack of data on the validity of the weight status estimation performed by observers trained in using this type of silhouette. Studying the accuracy of estimating weight status by structured observation would be an important step in validating this new methodology, which could be used as a simple and quick way to collect weight status data as an alternative to self-reported values whenever it is not possible to perform anthropometric measures.  
For the present investigation, it was hypothesized that estimated measures by observers trained in using body image scales might be used in assessing the weight status of adult individuals when it is not possible to perform anthropometric measures. As such, this study aimed to test the ability of trained observers to accurately classify adult individuals by structured observation regarding weight status, and to assess the concordance between observers in estimating the weight, height, and BMI categories of adult individuals.