Weight loss increases cardiovagal baroreflex function in obese young and older men

We tested the hypothesis that reductions in total body and abdominal visceral fat with energy restriction would be associated with increases in cardiovagal baroreflex sensitivity (BRS) in overweight/obese older men. To address this, overweight/obese (25 <= body mass index <= 35 kg/m(2)) young (OB-Y, n = 10, age = 32.9 +/- 2.3 yr) and older (OB-O, n = 6, age = 60+/- 2.7 yr) men underwent 3 mo of energy restriction at a level designed to reduce body weight by 5 - 10%. Cardiovagal BRS ( modified Oxford technique), body composition (dual-energy X-ray absorptiometry), and abdominal fat distribution ( computed tomography) were measured in the overweight/obese men before weight loss and after 4 wk of weight stability at their reduced weight and compared with a group of nonobese young men (NO-Y, n = 13, age = 21.1 +/- 1.0 yr). Before weight loss, cardiovagal BRS was similar to 35% and similar to 60% lower ( P < 0.05) in the OB-Y and OB-O compared with NO-Y. Body weight (- 7.8 +/- 1.1 vs. - 7.3 +/- 0.7 kg), total fat mass (- 4.1 +/- 1.0 vs. - 4.4 +/- 0.8 kg), and abdominal visceral fat ( - 27.6 +/- 6.9 vs. - 43.5 +/- 10.1 cm(2)) were reduced ( all P < 0.05) after weight loss, but the magnitude of reduction did not differ ( all P > 0.05) between OB-Y and OB-O, respectively. Cardiovagal BRS increased (11.5 /- 1.9 vs. 18.5 +/- 2.6 ms/mmHg and 6.7 +/- 1.2 vs. 12.8 +/- 4.2 ms/mmHg) after weight loss ( both P < 0.05) in OB-Y and OB-O, respectively. After weight loss, cardiovagal BRS in the obese/overweight young and older men was similar to 105% and similar to 73% ( P > 0.05) of NO-Y (17.5 +/- 2.2 ms/mmHg). Therefore, the results of this study indicate that weight loss increases the sensitivity of the cardiovagal baroreflex in overweight/obese young and older men.