title: No insulating effect of obesity.
abstract: The development of obesity may be aggravated if obesity itself insulates against heat loss and thus diminishes the amount of food burnt for body temperature control. This would be particularly important under normal laboratory conditions where mice experience a chronic cold stress (at ≈20°C). We used Scholander plots (energy expenditure plotted against ambient temperature) to examine the insulation (thermal conductance) of mice, defined as the inverse of the slope of the Scholander curve at subthermoneutral temperatures. We verified the method by demonstrating that shaved mice possessed only half the insulation of nonshaved mice. We examined a series of obesity models [mice fed high-fat diets and kept at different temperatures, classical diet-induced obese mice, ob/ob mice, and obesity-prone (C57BL/6) vs. obesity-resistant (129S) mice]. We found that neither acclimation temperature nor any kind or degree of obesity affected the thermal insulation of the mice when analyzed at the whole mouse level or as energy expenditure per lean weight. Calculation per body weight erroneously implied increased insulation in obese mice. We conclude that, in contrast to what would be expected, obesity of any kind does not increase thermal insulation in mice, and therefore, it does not in itself aggravate the development of obesity. It may be discussed as to what degree of effect excess adipose tissue has on insulation in humans and especially whether significant metabolic effects are associated with insulation in humans.
authors.affiliation: Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden; and Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Fischer
authors.affiliation: Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden; and.
authors.forename: Robert I
authors.initials: RI
authors.lastname: Csikasz
authors.affiliation: Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden; and.
authors.forename: Gabriella
authors.initials: G
authors.lastname: von Essen
authors.affiliation: Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden; and.
authors.forename: Barbara
authors.initials: B
authors.lastname: Cannon
authors.affiliation: Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden; and jan@metabol.su.se.
authors.forename: Jan
authors.initials: J
authors.lastname: Nedergaard
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D001823:Body Composition; D001833:Body Temperature Regulation; D002153:Calorimetry, Indirect; D003080:Cold Temperature; D059305:Diet, High-Fat; D004734:Energy Metabolism / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D009765:Obesity; D013814:Thermal Conductivity
keywords: insulation; ob/ob; obesity