A prospective study of fitness, fatness, and depressive symptoms.

Being overweight or obese might be a risk factor for developing depression. It is also possible that low cardiorespiratory fitness, rather than overweight or obesity, is the better predictor of depressive symptom onset. Adults in the Aerobics Center Longitudinal Study (Dallas, Texas) underwent fitness and fatness assessments between 1979 and 1998 and later completed a questionnaire about depressive symptoms in 1990, 1995, or 1999. Separate logistic regression models were used to test the associations between 3 fatness measures (body mass index, waist circumference, and percentage of body fat) and the onset of depressive symptoms. Analyses were repeated using fitness as the predictor variable. Additional analyses were performed to study the joint association of fatness and fitness with the onset of depressive symptoms. After controlling for fitness, no measure of fatness was associated with the onset of depressive symptoms. In joint analyses, low fitness was more strongly associated with the onset of elevated depressive symptoms than was fatness, regardless of the measure of fatness used. Overall, results from the present study suggest that low fitness is more strongly associated with the onset of elevated depressive symptoms than is fatness. To reduce the risk of developing depression, individuals should be encouraged to improve their fitness regardless of body fatness.