Influence of mild cold on 24 h energy expenditure, resting metabolism and diet-induced thermogenesis

Abstract

1. It has been suggested previously that people in developed countries do not expose themselves to cold severe enough to induce a metabolic response. The energy expenditure, as both heat production and total heat loss, of nine women was therefore measured continuously while each lived for 30 h in a whole-body calorimeter on two occasions, one at 2 8 O and the other at 22". All subjects followed a predetermined pattern of activity and food intake. The environmental conditions were judged by the subjects to be within those encountered in everyday life. In the standard clothing worn, 28O was considered to be comfortably warm but not too hot, while 22O was judged to be cool but not too cold. 2.Heat production for 24 h was significantly greater at the lower temperature, by (meanf SE) 7.0k 1.1 %. The range was between 2 and 12%. Total heat loss was also significantly greater, by 6%, and there was a large change in the partition of heat loss. At the lower temperature sensible heat loss increased by 29% while evaporative heat loss decreased by 39%.3. Resting metabolism measured in the morning 12-13 h after the last meal was significantly greater at 22O than at 28O, whereas there was no difference when the resting measurement was made for 2.5 h following a meal. 4.In conclusion : (a) environmental temperature may play a more important role than was previously recognized in the energy balance of those living in this country, and (b) there is an indication of at least a partial replacement of cold-induced by diet-induced thermogenesis in man.

Energy metabolism in humans at a lowered ambient temperature

“…The increased EE with lowered ambient temperature is consistent with the findings reported by Hardy andDu Bois (1943, 1940), Dauncey (1981), Werner (1981), and by Blaza & Garrow (1983) with different magnitudes of changes in ambient temperature between 30 and 10 C. The increase in SMR is similar to the findings reported by Hardy and Du Bois in women (1940) and the observation by Dauncey (1981), who in fact measured BMR and not SMR. The increase in 24 h DIT not only concerned the absolute value, but also the relative value, ie the percentage of total EI.…”

“…A significant relationship between body temperature and metabolic rate (Kobayashi, 1988;Kraeuchi & Wirz-Justice, 1994;Refinetti, 1997), as well as between ambient temperature and metabolic rate has been shown. In older (Hardy, 1934;Hardy & Du Bois, 1934, 1940Du Bois, 1936;Hardy & Milhorat, 1939), as well as in more recent studies (Dauncey, 1981;Werner, 1981;Blaza & Garrow, 1983) an inverse relationship between metabolic rate and ambient temperatures between 10 and 30 C has been observed. Until now, changes in energy metabolism have been mainly observed as changes in total or basic metabolic rate.…”

“…Since the difference in DIT cannot completely be explained by the difference in EI, we suggest that the remainder of the increased DIT might have been its facultative component, contributing to preventing a greater decrease in core body temperature. In the study by Dauncey (1981), BMR was also measured during 2 -5 h after lunch, thus in fact DIT was also measured, and no differences between the two circumstances with different ambient temperatures were found. The different result might be caused by the difference in the procedure.…”

“…Most of the studies mentioned only executed the measurements for a few hours. The study by Dauncey (1981) assessed total and basal metabolic rate during 24 h, while DIT was measured for a few hours. Mild cold exposure was 22 C, which was compared to 28 C, in women.…”

Influence of mild cold on the components of 24 hour thermogenesis in rats.

“…This compares with an immediate doubling or tripling in metabolic rate of the rat on exposure to severe cold of 15 'C (Sellers, Scott & Thomas, 1954), a doubling in 24 h oxygen consumption of mice kept singly at 15 compared with 29 or 31°C (Mount & Willmott, 1967) and an average 7 % increase in 24 h energy expenditure of women at 22 compared with 28°C when living under controlled conditions of food intake, major activity, clothing and bedding (Dauncey, 1981). The present finding is of practical significance for animals living at 'normal' room temperatures which are below thermal neutrality, especially if they are kept singly and without bedding.…”