Correlation between Body Mass Index and Waist-Hip Ratio amongst First Year Medical Students in Central Gujarat, India

Abstract

Introduction: Body Mass Index (BMI) and Waist–Hip Ratio (WHR) are common anthropometric indices to assess adiposity. However, BMI does not distinguish between lean mass and fat distribution, which limit its accuracy in identifying central obesity. This study aimed to assess the correlation between BMI and WHR among first-year medical students and to compare obesity prevalence based on these indices. Methods: A cross-sectional study was conducted among first-year medical students. Anthropometric measurements, including height, weight, waist and hip circumference, were recorded using standardised methods. WHO criteria used for BMI, WHR was interpreted using gender-specific cut-offs for central obesity. The correlation between BMI and WHR was evaluated using Pearson’s correlation coefficient, and agreement between the two classifications was assessed using the Kappa statistic. Results: Most participants had BMI and WHR values within normal limits. The overall prevalence of overweight and obesity based on BMI was modest, higher among males than females. However, when assessed using WHR, central obesity was found to be more prevalent among males. No significant correlation was observed between BMI and WHR (r≈0). The Kappa statistic (κ=0.019; SE=0.076; 95%CI) indicated only slight agreement between BMI- and WHR-based classifications, suggesting that these indices measure different aspects of body composition. Conclusion: BMI and WHR reflect distinct dimensions of adiposity. Relying solely on BMI may underestimate central obesity, particularly in males. Routine use of both BMI and WHR in health screening among young adults is recommended for early identification of individuals at risk for non-communicable diseases.