Abstract
We investigated how the sweating and shivering thresholds were affected by starvation in humans. Three male and 5 female volunteers were fasted for 24 hours (13:00-13:00h). Rectal temperature (Tre) and skin temperatures at 7 sites were measured with thermistors. Sweating rates at the forearm and chest were measured by a capsule ventilation method. The subjects were rested in a chair at an ambient temperature of 26°C and relative humidity of 45%. Then, both legs were immersed in warm water (42°C) and sweating was induced. After a 20 min-rest and blood sampling, the subjects had cold isotonic water with their both legs immersed in cold water (15°C), and shivering was induced. Tre and mean body temperature (Tmean) at the onsets of sweating and shivering were determined. In the fasting condition, the plasma levels of free fatty acid and leptin and plasma osmolality were significantly lower than those in the control condition. The 24-hour fast significantly decreased the threshold Tre and Tmean for shivering, but did not affect the threshold Tre and Tmean for sweating. The results suggest that in humans, fasting inhibits the activations of metabolic response to cold stimuli, which may be beneficial to conserve energy. However, short-term starvation has little effect on the heat loss system. [Jpn J Physiol 54 Suppl:S230 (2004)]
