Effects of short-term food deprivation on sweating and shivering thresholds

Starvation is known to lower the threshold core temperature for thermogenesis and then body core temperature in animals. However, little attention has been paid to the effects of food deprivation on heat loss mechanisms, especially in humans. We therefore determined the threshold temperatures for sweating and also shivering in humans after a 24-hour starvation. The subjects rested on a chair at an ambient temperature of 26℃ and relative humidity of 45%. Their rectal temperature (Tre) and skin temperatures at 7 body sites were continuously measured. Then, they were warmed or cooled by bathing both legs in warm (42℃) or cold water (15℃), respectively. Tre and skin temperatures at the onsets for thermally-induced sweating and shivering were determined, and threshold mean body temperatures (Tb) for them were calculated. The 24-hour food deprivation significantly lowered the threshold Tb for shivering, but did not affect the sweating thresho]d Tb. The results suggest that, in humans, the interthreshold zone is widened by food deprivation solely due to a decrease in the threshold for the activation of thermogenesis.