title: The thermogenic responses to overfeeding and cold are differentially regulated.
abstract: OBJECTIVE
  Brown adipose tissue (BAT) is a highly metabolic tissue that generates heat and is negatively associated with obesity. BAT has been proposed to mediate both cold-induced thermogenesis (CIT) and diet-induced thermogenesis (DIT). Therefore, it was investigated whether there is a relationship between CIT and DIT in humans.
  
  
  METHODS
  Nine healthy men (23 ± 3 years old, 23.0 ± 1.8 kg m(-2) ) completed 20 min of cold exposure (4°C) 5 days per week for 4 weeks. Before and after the intervention, CIT (the increase in resting metabolic rate at 16°C relative to 22°C) was measured by a ventilated hood indirect calorimeter, whereas DIT was measured as the 24-h thermic response to 1 day of 50% overfeeding (TEF150% ) in a respiratory chamber.
  
  
  RESULTS
  After the cold intervention, CIT more than doubled from 5.2% ± 14.2% at baseline to 12.0% ± 11.1% (P = 0.05), in parallel with increased sympathetic nervous system activity. However, 24-h energy expenditure (2,166 ± 206 vs. 2,118 ± 188 kcal day(-1) ; P = 0.15) and TEF150% (7.4% ± 2.7% vs. 7.7% ± 1.6%; P = 0.78) were unchanged. Moreover, there was no association between CIT and TEF150% at baseline or post-intervention, nor in their changes (P ≥ 0.47).
  
  
  CONCLUSIONS
  Cold acclimation resulted in increased CIT but not TEF150% . Therefore, it is likely that CIT and DIT are mediated by distinct regulatory mechanisms.
authors.affiliation: John S. McIlhenny Skeletal Muscle Physiology Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA.
authors.forename: Courtney M
authors.initials: CM
authors.lastname: Peterson
authors.affiliation: John S. McIlhenny Skeletal Muscle Physiology Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA.|Faculty of Sciences, Department of Medicine, University of Fribourg, Switzerland.
authors.forename: Virgile
authors.initials: V
authors.lastname: Lecoultre
authors.affiliation: John S. McIlhenny Skeletal Muscle Physiology Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Frost
authors.affiliation: John S. McIlhenny Skeletal Muscle Physiology Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Simmons
authors.affiliation: John S. McIlhenny Skeletal Muscle Physiology Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA.
authors.forename: Leanne M
authors.initials: LM
authors.lastname: Redman
authors.affiliation: John S. McIlhenny Skeletal Muscle Physiology Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Ravussin
mesh_terms: D002001:Adipose Tissue, Brown / Q000378:metabolism; D000328:Adult; D001794:Blood Pressure; D002153:Calorimetry, Indirect; D003080:Cold Temperature / Q000009:adverse effects; D004734:Energy Metabolism / Q000502:physiology; D006339:Heart Rate; D006801:Humans; D006963:Hyperphagia / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D013564:Sympathetic Nervous System / Q000502:physiology; D022722:Thermogenesis / Q000502:physiology*; D055815:Young Adult