title: Individual thermogenic responses to mild cold and overfeeding are closely related.
abstract: BACKGROUND
  Adaptive thermogenesis is defined as the increase in energy expenditure in response to overfeeding or cold. Large interindividual differences in adaptive thermogenesis have been described.
  
  
  OBJECTIVE
  Because there are indications for a common underlying mechanism, we studied in humans whether the increase in thermogenesis during short-term overfeeding (3 d) is related to mild cold-induced thermogenesis.
  
  
  METHODS
  Thirteen lean male subjects have been exposed to three experimental conditions in respiration chambers: baseline (36 h in energy balance at thermoneutrality, 22 C), overfeeding (84 h at 160% of energy balance, 22 C), and mild cold (84 h in energy balance, 16 C).
  
  
  METHODS
  During the interventions, total daily energy expenditure (TDEE), physical activity, skin temperatures, and core temperature were measured. After each condition, fasting plasma norepinephrine concentration was measured.
  
  
  RESULTS
  Overfeeding caused significant increases in TDEE (0.77 MJ/d, P < 0.001). During cold exposure TDEE increased significantly (0.59 MJ/d, P < 0.005), whereas physical activity decreased. The changes in TDEE during both overfeeding and mild cold exposure showed considerable interindividual variation (respectively, -0.11 to 1.61 MJ/d and -0.19 to 1.58 MJ/d). The individual changes in energy expenditure during mild cold exposure and overfeeding were highly correlated (P < 0.005). Fasting norepinephrine plasma concentrations correlated significantly to energy expenditure in both situations (P < 0.05).
  
  
  CONCLUSIONS
  These results suggest that both overfeeding-induced and mild cold-induced adaptive thermogenesis share common regulating mechanisms. This indicates that cold exposure could be used as a biomarker for the individual thermogenic response to excess energy intake.
authors.affiliation: Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht, Maastricht University, 6200 MD Maastricht, The Netherlands. S.Wijers@hb.unimaas.nl
authors.forename: Sander L J
authors.initials: SL
authors.lastname: Wijers
authors.forename: Wim H M
authors.initials: WH
authors.lastname: Saris
authors.forename: Wouter D
authors.initials: WD
authors.lastname: van Marken Lichtenbelt
mesh_terms: D000328:Adult; D001823:Body Composition / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology*; D003080:Cold Temperature; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D006728:Hormones / Q000097:blood; D006801:Humans; D006963:Hyperphagia / Q000503:physiopathology*; D008297:Male; D012881:Skin Temperature / Q000502:physiology