The trend of BMI values of US adults by deciles, birth cohorts 1882-1986 stratified by gender and ethnicity.

We estimate trends in BMI values by deciles of the US adult population by birth cohorts 1882-1986 stratified by ethnicity and gender. The highest decile increased by some 18-22 BMI units in the course of the century while the lowest ones increased by merely 1-3 BMI units. For example, a typical African American woman in the 10th percentile and 64 in. (162.6 cm) tall increased in weight by just 12 pounds (5 kg) whereas in the 90th percentile her weight would have increased by 128 pounds (58 kg). Hence, the BMI distribution became increasingly right skewed as the distance between the deciles increased considerably. The rate of change of the BMI decile curves varied greatly over time and across gender and ethnicity. The BMI deciles of white men and women experienced upswings after the two world wars and downswings during the Great Depression and also decelerated after 1970. However, among African Americans the pattern is different during the first half of the century with men's rate of increase in BMI values decreasing substantially and that of females remaining constant at a relatively high level until the Second World War. After the war, though, the rate of change of BMI values of blacks came to resemble that of whites with an accelerating phase followed by a slowdown around the 1970s.