title: A randomized trial of cold-exposure on energy expenditure and supraclavicular brown adipose tissue volume in humans.
abstract: OBJECTIVE
  To study if repeated cold-exposure increases metabolic rate and/or brown adipose tissue (BAT) volume in humans when compared with avoiding to freeze.
  
  
  METHODS
  Randomized, open, parallel-group trial.
  
  
  METHODS
  Healthy non-selected participants were randomized to achieve cold-exposure 1hour/day, or to avoid any sense of feeling cold, for 6weeks. Metabolic rate (MR) was measured by indirect calorimetry before and after acute cold-exposure with cold vests and ingestion of cold water. The BAT volumes in the supraclavicular region were measured with magnetic resonance imaging (MRI).
  
  
  RESULTS
  Twenty-eight participants were recruited, 12 were allocated to controls and 16 to cold-exposure. Two participants in the cold group dropped out and one was excluded. Both the non-stimulated and the cold-stimulated MR were lowered within the group randomized to avoid cold (MR at room temperature from 1841±199 kCal/24h to 1795±213 kCal/24h, p=0.047 cold-activated MR from 1900±150 kCal/24h to 1793±215 kCal/24h, p=0.028). There was a trend towards increased MR at room temperature following the intervention in the cold-group (p=0.052). The difference between MR changes by the interventions between groups was statistically significant (p=0.008 at room temperature, p=0.032 after cold-activation). In an on-treatment analysis after exclusion of two participants that reported ≥8days without cold-exposure, supraclavicular BAT volume had increased in the cold-exposure group (from 0.0175±0.015l to 0.0216±0.014l, p=0.049).
  
  
  CONCLUSIONS
  We found evidence for plasticity in metabolic rate by avoiding to freeze compared with cold-exposure in a randomized setting in non-selected humans.
authors.affiliation: Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden; Department of Biomedical Engineering, Linköping University, Linköping, Sweden.
authors.forename: Thobias
authors.initials: T
authors.lastname: Romu
authors.affiliation: Department of Medical and Health Sciences, Faculty of Medicine and Health Sciences, Linköping University.
authors.forename: Camilla
authors.initials: C
authors.lastname: Vavruch
authors.affiliation: Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Olof
authors.initials: O
authors.lastname: Dahlqvist-Leinhard
authors.affiliation: Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Joakim
authors.initials: J
authors.lastname: Tallberg
authors.affiliation: Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Nils
authors.initials: N
authors.lastname: Dahlström
authors.affiliation: Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Persson
authors.affiliation: Department of Medical and Clinical Genetics, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Heglind
authors.affiliation: Department of Medical and Clinical Genetics, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Martin E
authors.initials: ME
authors.lastname: Lidell
authors.affiliation: Department of Medical and Clinical Genetics, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Sven
authors.initials: S
authors.lastname: Enerbäck
authors.affiliation: Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden; Department of Biomedical Engineering, Linköping University, Linköping, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Borga
authors.affiliation: Department of Medical and Health Sciences, Faculty of Medicine and Health Sciences, Linköping University. Electronic address: fredrik.h.nystrom@liu.se.
authors.forename: Fredrik H
authors.initials: FH
authors.lastname: Nystrom
mesh_terms: D002001:Adipose Tissue, Brown / Q000000981:diagnostic imaging* / Q000378:metabolism*; D000328:Adult; D002153:Calorimetry, Indirect; D003080:Cold Temperature; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009929:Organ Size / Q000502:physiology; D022722:Thermogenesis / Q000502:physiology*; D055815:Young Adult
keywords: Brown adipose tissue; Cold exposure; Magnetic resonance imaging; Metabolic rate