Short‐term fasting‐induced autonomic activation and changes in catecholamine levels are not mediated by changes in leptin levels in healthy humans

Abstract

The findings of this controlled, interventional study indicate that changes in heart rate, catecholamine levels and cardiac vagal modulation associated with 72-h fasting are independent of regulation by leptin. Thus, changes in leptin levels within the physiological range do not seem to play a role in regulating autonomic function during short-term starvation in healthy humans.

Sympathetic-leptin relationship in obesity: effect of weight loss

“…In contrast, the LF component of HRV was markedly reduced with sibutramine as in the placebo group. These paradoxical changes with sibutramine are consistent with previous studies on healthy subjects and suggest a combination of peripheral and central nervous system mechanisms [16,17]. Low-frequency heart rate oscillations, the so-called Mayer waves, are mediated by the SNS.…”

“…In healthy humans, changes to leptin levels within the physiological range during short-term fasting do not seem to influence LF power or LF/HF balance [16]. Nevertheless, a 72-hour fasting leads to an increase in SNS activity because of the decrease in glycemia, whereas serum leptin levels dramatically decreased.…”

Human cardiac autonomic responses to head-up tilting during 72-h starvation

“…Others (Webber and MacDonald 1994) reported that during a 3-day fast in healthy humans, elevations in resting metabolic rate, heart rate, and forearm blood flow were consistent with an increased sympathetic nervous system activity. Also, starvation-induced increases in muscle sympathetic nerve activity (Andersson et al 1988) and an increased heart rate with reduced vagal modulation (Chan et al 2007) are further evidence of an increase in sympathetic autonomic nervous system activity with short periods of starvation in humans. In contrast, decreased resting sympathetic activation in acutely anorexic and fasting These data were obtained from subject 6 on Day 3 p.m., where mean supine heart rate was 55.6 beats min -1 , and mean heart rate during head-up tilt was 86 beats min -1…”

“…For example, a 48-h fast caused suppression of centrally mediated sympathetic activity in the rat as evidenced by the reduced turnover of norepinephrine in the heart and other organs (Young and Landsberg 1977). Similarly in obese humans, the decrease in blood pressure which accompanies short-term calorie restriction has been attributed to a reduction in sympathetic nervous system activity (Lansberg and Young 1979;Jung et al 1979;Andersson et al 1991), although this is not a consistent viewpoint (Andersson et al 1988;Chan et al 2007;Messaoudi et al 1998). For example, it has been reported that the reduction in blood pressure during 8 days of semi-starvation was not accompanied by a decrease in sympathetic nerve activity (Messaoudi et al 1998), with no change in heart rate or urinary catecholamine excretion observed.…”

Food Cues Do Not Modulate the Neuroendocrine Response to a Prolonged Fast in Healthy Men

“…The increase in RMR during short-term fasting might be due to the energy costs of a temporary increase in gluconeogenesis and ketogenesis [24]. Activation of the sympathetic nervous system may modify RMR during prolonged fasting [27]. In apparent contrast, RMR is clearly reduced after longer-term calorie restriction and weight loss in obese humans [28], but this is probably due to the significant loss of lean body mass in this context [29].…”