Component distributions of body mass index defining moderate and extreme overweight in Danish women and men.

Skewness in the distribution of body mass index in a population of Danish men (n = 1,589) and women (n = 1,988) adopted in Copenhagen between 1923 and 1947 can be explained by mixture of three component distributions, after removing age and sex effects. Even when residual skewness was allowed for in component distributions, similar results were obtained. The upper component distributions corresponded to extreme overweight in both women and men. The results indicate that while there are differences in the means and ranges of body mass index in men and women, the component distributions are similar. Both genetic and environmental factors can produce such component distributions. The authors speculate that the underlying predisposition to obesity is distributed similarly in women and men. Finally, on the basis of the component distributions, the authors propose thresholds of body mass index which allow for 85-98 per cent separation of moderate and extreme overweight groups in men and women.