Changes in the distribution of body mass index of white US men, 1890-2000

Objective: The study aimed to describe changes in the distribution of body mass index (BMI) among white non-Hispanic US men aged 40-69 years throughout the 20th century. Subjects: The subjects were 12 312 randomly drawn Union Army veterans examined between 1890 and 1900, and 4059 NHANES (National Health and Nutrition Examination Survey) participants examined between 1976 and 2000. Method: The study compared descriptive statistics of the age- and year-specific distributions of BMI. Results: Between 1890 and 2000, median BMI of men aged 50-59 years increased by 5.7 kg/m(2) (25%), while the standard deviation almost doubled. In this age group, the current distribution of BMI is less right-skewed than in the earlier cohort. Obesity prevalence increased from 3.4% to 35%. In 1890-1894, median BMI declined with age, but by 2000 the age pattern had been reversed. The average annual growth rate of median BMI was lowest between 1900 and 1976 and has been rising to 0.5% per annum between 1988 and 2000. Conclusions: The increase in median BMI accounts for 75% of the rise in obesity prevalence between 1890 and 2000. The remainder must be attributed to changes in other features of the distribution, most notably the increased variance of BMI.