title: Heat production and body temperature during cooling and rewarming in overweight and lean men.
abstract: OBJECTIVE
  To compare overweight and lean subjects with respect to thermogenesis and physiological insulation in response to mild cold and rewarming.
  
  
  METHODS
  Ten overweight men (mean BMI, 29.2 +/- 2.8 kg/m(2)) and 10 lean men (mean BMI, 21.1 +/- 2.0 kg/m(2)) 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Human Biology, NUTRIM (Nutrition and Toxicology Research Institute Maastricht), Maastricht University, Maastricht, The Netherlands. m.vanooijen@HB.unimaas.nl
authors.forename: Anne M J
authors.initials: AM
authors.lastname: Claessens-van Ooijen
authors.forename: Klaas R
authors.initials: KR
authors.lastname: Westerterp
authors.forename: Loek
authors.initials: L
authors.lastname: Wouters
authors.forename: Paul F M
authors.initials: PF
authors.lastname: Schoffelen
authors.forename: Anton A
authors.initials: AA
authors.lastname: van Steenhoven
authors.forename: Wouter D
authors.initials: WD
authors.lastname: van Marken Lichtenbelt
mesh_terms: D000328:Adult; D001823:Body Composition / Q000502:physiology; D015992:Body Mass Index; D001833:Body Temperature Regulation / Q000502:physiology*; D002153:Calorimetry, Indirect; D003080:Cold Temperature; D006801:Humans; D008297:Male; D050177:Overweight / Q000502:physiology*; D017694:Rewarming; D012768:Shivering / Q000502:physiology; D012879:Skin Physiological Phenomena; D022722:Thermogenesis / Q000502:physiology*; D013851:Thinness