We tested the hypothesis that modest, overfeeding-induced weight gain would increase sympathetic neural activity in nonobese humans. Twelve healthy males (23 ± 2 years; body mass index, 23.8 ± 0.7) were overfed ∼1,000 kcal/day until a 5-kg weight gain was achieved. Muscle sympathetic nerve activity (MSNA, microneurography), blood pressure, body composition (dual energy X-ray absorptiometry), and abdominal fat distribution (computed tomography) were measured at baseline and following 4 wk of weight stability at each individual's elevated body weight. Overfeeding increased body weight (73.5 ± 3.1 vs. 78.4 ± 3.2 kg, P < 0.001) and body fat (14.9 ± 1.2 vs. 18 ± 1.1 kg, P < 0.001) in 42 ± 8 days. Total abdominal fat increased (220 ± 22 vs. 266 ± 22 cm2, P < 0.001) with weight gain, due to increases in both subcutaneous (158 ± 15 vs. 187 ± 12 cm2, P < 0.001) and visceral fat (63 ± 8 vs. 79 ± 12 cm2, P = 0.004). As hypothesized, weight gain elicited increases in MSNA burst frequency (32 ± 2 vs. 38 ± 2 burst/min, P = 0.002) and burst incidence (52 ± 4 vs. 59 ± 3 bursts/100 heart beats, P = 0.026). Systolic, but not diastolic blood pressure increased significantly with weight gain. The change in MSNA burst frequency was correlated with the percent increase in body weight ( r = 0.59, P = 0.022), change in body fat ( r = 0.52, P = 0.043) and percent change in body fat ( r = 0.51, P = 0.045). The results of the current study indicate that modest diet-induced weight gain elicits sympathetic neural activation in nonobese males. These findings may have important implications for understanding the link between obesity and hypertension.
Estrogen Deficiency and the Origin of Obesity during Menopause
