Diagnostic discordance between BMI and adiposity in physically active adults
DOI:
https://doi.org/10.47197/retos.v75.118279Keywords:
Adipose tissue, body composition, body mass index, exercise, obesityAbstract
Introduction: Body mass index is universally used to classify weight status, but its validity to reflect actual adiposity in populations performing regular physical exercise is questioned. It is critical to analyze its structural limitations against methods that discriminate body composition components.
Objective: The objective was to evaluate the diagnostic concordance and accuracy of body mass index versus body fat percentage, as well as to identify the factors associated with discordance in physically active adults.
Methodology: A quantitative cross-sectional study was conducted with 973 participants from a fitness center. The weight classification of the world health organization was compared against the fat percentage estimated by multi-frequency electrical bioimpedance according to the American Council on Exercise criteria, analyzing concordance using the kappa coefficient and logistic regression models.
Results: The results showed a practically null concordance between both methods, with a kappa coefficient of 0.03, and a sensitivity of barely 23.3% for body mass index to detect obesity. Diagnostic discordance affected 34.3% of the sample, with the advanced level of training experience, with an odds ratio of 21.47, being the main predictor of error due to muscle mass.
Discussion: The findings were contrasted with recent literature, confirming that the traditional anthropometric indicator generates false positives in subjects with muscular adaptations and false negatives in cases of hidden obesity with normal weight.
Conclusions: It is concluded that body mass index presents insufficient validity to evaluate active adults, making it imperative to transition towards direct body composition methods.
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