We studied the effects of a hypocaloric diet (D, n = 24, age: 32.2 +/- 1.4 yr, body mass index: 34.7 +/- 0.5 kg/m2) and a hypocaloric diet associated with exercise training (D + T, n = 25, age: 32.3 +/- 1.3 yr, body mass index: 32.9 +/- 0.4 kg/m2) on muscle metaboreflex control, muscle sympathetic nerve activity (MSNA, microneurography), blood pressure, and forearm blood flow (plethysmography) levels during handgrip exercise at 10% and 30% of maximal voluntary contraction in normotensive obese women. An additional 10 women matched by age and body mass index were studied as a nonadherent group. D or D + T significantly decreased body mass index. D or D + T significantly decreased resting MSNA (bursts/100 heartbeats). The absolute levels of MSNA were significantly lower throughout 10% and 30% exercise after D or D + T, although no change was found in the magnitude of response of MSNA. D + T, but not D, significantly increased resting forearm vascular conductance. D + T significantly increased the magnitude of the response of forearm vascular conductance during 30% exercise. D or D + T significantly increased MSNA levels during posthandgrip circulatory arrest when muscle metaboreflex is isolated. In conclusion, weight loss improves muscle metaboreflex control in obese women. Weight loss reduces MSNA, which seems to be centrally mediated. Weight loss by D + T increases forearm vascular conductance at rest and during exercise in obese individuals.

OBJECTIVE:We tested the hypothesis that muscle sympathetic nerve activity (MSNA) and forearm vascular resistance (FVR) would be augmented during mental stress or cold pressor test in healthy obese individuals compared with healthy lean individuals.RESEARCH METHODS AND PROCEDURES:Twenty-nine healthy obese women and 12 age-matched healthy lean women were involved in the study. MSNA was directly measured from the peroneal nerve using microneurography. Forearm blood flow was measured by venous occlusion plethysmography. Blood pressure (BP) was monitored noninvasively by an automatic BP cuff, and heart rate (HR) was measured by electrocardiogram. Stroop color word test was performed for 4 minutes, and the cold pressor test was performed for 2 minutes.RESULTS:Baseline MSNA and FVR were greater in the obese group than in the lean group. BP and HR were similar between groups. During mental stress, MSNA and FVR were greater in obese individuals than in lean individuals, although the magnitude of response was similar between groups. BP and HR similarly increased in obese and lean individuals. During the cold pressor test, MSNA, FVR, and BP were greater in obese individuals, but the magnitude of response was similar between groups. HR increased similarly during the cold pressor test in both obese and lean individuals.DISCUSSION:Obesity increases MSNA and FVR during mental stress and the cold pressor test. This inappropriate neurovascular control can be expected to have an adverse effect on the risk factors for cardiovascular events and, hence, should be considered in the treatment of obese patients.