Fractionating healthy weight.

Any discussion of healthy weight necessarily starts with body composition and its relation to long-term mortality and morbidity and then goes on to consider the limited range of ages for which we have epidemiologic data, the time span involved, the criteria used to define "healthy," and the possibility that a weight that is advantageous with respect to one outcome criterion may be disadvantageous for another. One may therefore ask, weight of what? healthy weight for whom? by what criteria? and question whether a simple weight-for-height ratio is sufficiently effective for the task.