Thermoregulatory sympathetic nervous system activity and diet‐induced waist‐circumference reduction in obese Japanese women

Abstract

The present study is designed to investigate how and to what extent sympathovagal behavior in a balanced low-calorie diet relates to favorable changes of body mass, waist circumference, and/or metabolic risk factors. The study involved 28 mildly obese women without clinical complications, who underwent an 8-week calorie restriction program using a 1,200-kcal daily diet with an adequate nutrient content; including two regular meals, and one formula meal replacement. All subjects were examined before and after the dietary intervention. We measured anthropometric parameters, blood pressure, and biochemical blood profiles for lipid metabolism. Autonomic nervous system activity was evaluated by heart rate variability power spectral analysis. The dietary intervention induced moderate, but significant reduction of waist circumference (-5.3% +/- 0.8%), body fat percentage (-5.8% +/- 0.8%), and body mass (-6.6% +/- 0.5%). Linear regression analysis showed that Deltavery low frequency (VLF) power reflecting energy metabolic- and thermoregulatory sympathetic function significantly correlated to Deltawaist circumference (r = -0.53, P < 0.01), Deltabody fat percentage (r = -0.39, P < 0.05), Deltabody mass (r = -0.43, P < 0.05), DeltaHDL-cholesterol/total cholesterol ratio (HDL-C/TC) (r = 0.62, P < 0.001), and Deltanonesterified fatty acids (NEFA) (r = 0.56, P < 0.01). A stepwise multiple regression analysis additionally revealed that Deltawaist circumference (P = 0.024), DeltaHDL-C/TC (P = 0.013), and DeltaNEFA (P = 0.016) were significant and independent factors, which contributing to the variance in DeltaVLF power (r(2) = 0.61). Although causes and consequences of obesity continue to elude researchers, the present study indicates that thermoregulatory sympathetic activity relates to moderate waist-circumference reduction together with favorable changes of blood lipid profiles after short-term dietary modification in mildly obese women.

Effects of Infrared-LED Illumination Applied During High-Intensity Treadmill Training in Postmenopausal Women

“…30 Anthropometric data were used to determine the body mass index [BMI: body weight (in kg) divided by height (in m) squared] and the waist-hip ratio [waist (in cm) divided by hip (in cm)]. [29][30][31] For measurement of body fat and lean mass, the bipolar impedance of the upper limbs (OMRONÒ, Kyoto, Japan) 31 was performed, and the participants were instructed not to exercise, not to use metals in the body, and to maintain normal hydration status.…”

Associations of Metabolic Variables with Electrocardiographic Measures of Sympathovagal Balance in Healthy Young Adults

“…The very low frequency band (0.001-0.04 Hz) has been considered by the Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology (1996) guidelines to be too small to be a reliable indicator during short-term recordings. However, recent investigations have challenged this assertion (Nagai et al, 2005;Nagai et al, 2006;Fujibayashi et al, 2009) and we have found that 5-min recordings produced VLF measurements that represented a significant proportion (23%-52%) of the total heart rate spectral power expressed in normalized units. The present study was designed, partly, to test the physiological significance of the very low frequency band as an indicator of sympathetic thermoregulatory and metabolic energy signaling.…”

“…The guidelines for standardizing heart rate variability measurements state that the very low frequency spectral power may represent too small a proportion of the total spectral power to be worthy of analysis during short intervals of electrocardiographic recordings (Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology 1996). More recent studies have suggested that the very low frequency power could, under appropriate conditions, be an indicator of sympathetic thermoregulatory and metabolic energy signaling (Nagai et al, 2005;Nagai et al, 2006;Fujibayashi et al, 2009). The significant positive correlation between body temperature and very low frequency power that we found during fasting, but not during paced breathing, corroborates the previous reports of a thermoregulatory and metabolic energy signaling function of the very low frequency band.…”

“…We have demonstrated positive correlations of the low frequency/high frequency heart rate variability spectral power ratio with the respiratory quotient before and after feeding (Millis et al, 2009) and negative correlations with the percentage of body fat in healthy young adult/adolescent African-American males after overnight fasting; and the latter only during periods of uncontrolled, and not during periods of paced, breathing (Millis et al, 2010). Other researchers have reported that changes in the percentage of body fat may be correlated with changes in the very low frequency spectral power, a measure of sympathetic thermoregulatory and metabolic energy signaling (Fujibayashi et al, 2009). However, the significances of very low frequency spectral power to measures of body fat stores during trials of uncontrolled and paced breathing associated with different physiological states such as fasting or feeding remain unclear.…”

Impact of fat distribution on metabolic, cardiovascular and symptomatic aspects in postmenopausal women

“…The anatomical landmarks to measure the circumference (cm), in the upright position of the body were: 1) waist: measured at the above the iliac crest; 2) hip: measured at the largest protuberance of the buttocks [12]. The body fat and lean mass were measured by the bipolar electrical bioimpedance of the upper limbs (OMRON®, Kyoto, Japan) [13]. The measurements of the skinfolds (in mm) were performed in the upright position, the caliper was placed at specific locations on the right side of the body, which was relaxed and dry.…”