Does sympathoadrenal activity predict changes in body fat? An 18-y follow-up study.

BACKGROUND Whether alterations in the sympathoadrenal system contribute to obesity or, rather, are consequences of it, is an unresolved issue. OBJECTIVE We hypothesized that the sympathoadrenal system plays a predictive role in the development of body fat. DESIGN At entry, arterial plasma epinephrine and norepinephrine concentrations were measured in 99 healthy men (x +/- SD age: 19.3 +/- 0.4 y) at rest and during a mental stress test and a cold pressor test. Body mass index (BMI; in kg/m(2)), waist circumference, and triceps skinfold thickness were measured at entry and after 18 y of follow-up. RESULTS Eighty subjects (81%) were available for follow-up analyses after a mean (+/-SD) of 18.0 +/- 0.9 y. The epinephrine responses to the mental stress test (E(MST)) showed a negative relation to changes in BMI (P = 0.01) and waist circumference (P = 0.007). The mean increase in BMI was 6.3 among subjects in the lowest E(MST) quartile and 3.7 in the remaining subjects. In multiple regression analyses corrected for level of exercise, BMI, waist circumference, and triceps skinfold thickness at entry, E(MST) was found to be a consistent negative predictor of future BMI (P = 0.005), waist circumference (P = 0.001), and triceps skinfold thickness (P = 0.05). CONCLUSIONS We present the first long-term follow-up study in whites showing that the epinephrine response to mental stress is a negative predictor of future BMI, waist circumference, and triceps skinfold thickness after 18 y of follow-up. These findings may provide further insights into the pathophysiology of obesity.