How Well Does The Standard Body Mass Index Or Variations With A Different Exponent Predict Human Lifespan?

ObjectiveThe objective was twofold: (1) to estimate for each individual the body mass index (BMI) which is associated with the lowest risk of death, and (2) to study variants of the BMI formula to determine which gives the best predictions of death.MethodsTreating BMI=mass/height(2) as a continuous variable and estimating its interaction effects with several other variables, this study analyzed the NIH-AARP study data set of approximately 566,000 individuals and fit Cox proportional hazards models to the survival times.ResultsFor each individual, a personalized optimal BMI, the BMI for that individual which, according to the model, is associated with the lowest risk of death, is estimated. The average personalized optimal BMI is approximately 26, which is in the current overweight category. In fact, mass/height is a better predictor of death on the data set than BMI itself.ConclusionsThe model suggests that an individual's optimal BMI depends on his or her features; one-size-fits-all recommendations may be not best.