Two hypothetical normal distributions of BMI with equal means but different variances; increased variance gives a lower and broader shape compared to a distribution with less variance. Vertical line indicates cut-off value (BMI ≥ 25 kg/m2). The dark shaded area corresponds to the prevalence of overweight and obesity for the distribution with less variance, and the light shaded area corresponds to additional prevalence due to increased variance.
Biehl et al. BMC Public Health 2013 13:146 doi:10.1186/1471-2458-13-146