Unintentional weight loss in the United States.

Lower weight is usually considered advantageous to health, yet weight loss has been associated with increased mortality. An explanation for this paradox might be that the benefits of weight loss may depend on whether the loss is intentional or unintentional. The authors investigated whether intentional and unintentional weight loss differed in their associations with known risk factors for morbidity and mortality in a nationally representative sample of the US population. The sample consisted of 9,144 persons, aged 45 years and older, who answered questions regarding 1-year weight change in the diabetes risk factor Current Health Topic of the 1989 National Health Interview Survey (NHIS). Statistical analyses incorporated the sample weights and characteristics of the survey design. Relative to a common referent group, the factors associated with weight loss differed depending on whether the loss was defined as intentional loss, as unintentional loss, or regardless of intention. Restricting analysis to the 1,999 persons who lost weight, unintentional relative to intentional weight loss was significantly (p < 0.05) associated with older age, poorer health status, smoking, lower body mass index, and, in men only, widowhood and less education. Thus, unintentional weight loss may serve as a marker for factors that characterize persons at greater risk of mortality than persons undergoing intentional weight loss. Also, intention to lose weight may help clarify the relation between weight loss and mortality that, to this point, has shown counterintuitive results. Studies of the relation between weight loss and mortality should incorporate intention as a factor in the analysis.