1. ^*Department of Human Biology, NUTRIM (Nutrition and Toxicology Research Institute Maastricht), Maastricht University, Maastricht, The Netherlands
2. ^†Department of Energy Technology, University of Technology, Eindhoven, The Netherlands.

Correspondence: Anne M.J. Claessens-van Ooijen Department of Human Biology, Maastricht University, Universiteitssingel 50, P.O. Box 616, 6200 MD Maastricht, The Netherlands. E-mail: m.vanooijen@HB.unimaas.nl

^*The costs of publication of this article were defrayed, in part, by the payment of page charges. This article must, therefore, be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Received 13 July 2005; Accepted 2 August 2006.

Abstract

Objective: To compare overweight and lean subjects with respect to thermogenesis and physiological insulation in response to mild cold and rewarming.

Research Methods and Procedures: Ten overweight men (mean BMI, 29.2 2.8 kg/m²) and 10 lean men (mean BMI, 21.1 2.0 kg/m²) were exposed to cold air for 1 hour, followed by 1 hour of rewarming. Body composition was determined by hydrodensitometry and deuterium dilution. Heat production and body temperatures were measured continuously by indirect calorimetry and thermistors, respectively. Muscle activity was recorded using electromyography.

Results: In both groups, heat production increased significantly during cooling (lean, p = 0.004; overweight, p = 0.006). The increase was larger in the lean group compared with the overweight group (p = 0.04). During rewarming, heat production returned to baseline in the overweight group and stayed higher compared with baseline in the lean group (p = 0.003). The difference in heat production between rewarming and baseline was larger in the lean (p = 0.01) than in the overweight subjects. Weighted body temperature of both groups decreased during cold exposure (lean, p = 0.002; overweight, p < 0.001) and did not return to baseline during rewarming.

Discussion: Overweight subjects showed a blunted mild cold-induced thermogenesis. The insulative cold response was not different among the groups. The energy-efficient response of the overweight subjects can have consequences for energy balance in the long term. The results support the concept of a dynamic heat regulation model instead of temperature regulation around a fixed set point.