Modification of the relationship between the Quetelet index and mortality by weight-loss history among older women.

The effect of weight on mortality was examined using data from the first National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study for white women aged 65 to 74 years at baseline. There was a U-shaped curve relating the Quetelet index categories to total mortality, with increased risk for both lean and heavy women. However, the increased risk to lean subjects occurred only among those who had lost more than 8.55% from their reported lifetime maximum weight. Controlling for baseline medical conditions, excluding early years of follow-up, and limiting the analysis to never-smokers did not greatly change the results. Lean women with stable weight have the lowest risk of mortality, while those who have lost weight have a high risk. Heavy women have a high risk of mortality regardless of weight-loss history. Thus, the effect of weight on mortality is modified by history of weight loss in older women, even when accounting for factors associated with weight loss and increased mortality risk.