Body mass index (BMI)

Abstract

Obesity is a very prevalent problem in the US that impacts on health and mortality and is associated with billions of dollars in health care costs. The BMI, a measure of weight adjusted for height, is used widely throughout the world to identify obese individuals as well as the relationship between body mass and mortality. Obese BMI is generally considered a risk factor for mortality and this has been documented in studies of the general population as well as NFL players. Playing-time BMI based on weight and height while playing professional basketball and football is computed and tested as a risk factor. Nearly 90% of NFL players have either overweight (58.8%) or obese (30.8%) BMIs. Surprisingly, no NBA players are obese and only about 13% reach the overweight threshold. Controlling for year of birth in survival analysis, overweight BMI is a significant predictor of mortality risk within NBA players. However, obese BMI is required to significantly elevate mortality risk within NFL players. Mortality risk is increased by 40% in overweight NBA players and by 52% in obese NFL players. There are also significant between-league differences in mortality risk when BMI and year of birth are controlled. NBA players have a 29% increased mortality risk compared to NFL players when the categorical version of BMI is included in survival analysis. Given the absence of overlap at the obese end of the BMI scale between players in the two leagues, these results require scrutiny.