title: Changes in insulin sensitivity precede changes in body composition during 14 days of step reduction combined with overfeeding in healthy young men.
abstract: A lifestyle characterized by inactivity and a high-calorie diet is a known risk factor for impaired insulin sensitivity and development of Type 2 diabetes mellitus. To investigate possible links, nine young healthy men (24 ± 3 yr; body mass index of 21.6 ± 2.5 kg/m(2)) completed 14 days of step reduction (10,000 to 1,500 steps/day) and overfeeding (+50% kcal). Body composition (dual X-ray absorptiometry, MRI), aerobic fitness (maximal O(2) consumption), systemic inflammation and insulin sensitivity [oral glucose tolerance test (OGTT), hyperinsulinemic euglycemic clamp] were assessed before (day 0), during (days 3 and 7), and immediately after the intervention (day 14), with follow-up tests (day 30). Body weight had increased at days 7 and 14 (P < 0.05). The amount of visceral fat had increased at day 14 compared with day 0 (P < 0.05). The insulin response to the OGTT had increased at days 7 and 14 (P < 0.05). Insulin sensitivity, estimated using the Matsuda index, had decreased at days 3 and 7 (P < 0.01). At day 14, glucose infusion rates had decreased by ∼44% during the euglycemic clamps (P < 0.05). Also, plasma levels of leptin and adiponectin had increased (P < 0.05), whereas no changes were seen in inflammatory markers. At day 30, body weight and whole body adiposity were still elevated compared with day 0 (P < 0.05), whereas the insulin sensitivity as well as the insulin response to the OGTT did not differ from baseline. The glucose response to the OGTT was only affected at day 30, with a decrease compared with day 0. Our data show that insulin sensitivity was impaired after 3 days of inactivity and overfeeding. Impairments in insulin sensitivity occurred before changes in body composition, supporting the notion that the initial steps in impairment of insulin sensitivity may be linked directly to the effects of inactivity and a high calorie intake.
authors.affiliation: The Centre of Inflammation and Metabolism, Department of Infectious Diseases and CMRC, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. shknudsen@inflammation-metabolism.dk
authors.forename: Sine Haugaard
authors.initials: SH
authors.lastname: Knudsen
authors.forename: Louise Seier
authors.initials: LS
authors.lastname: Hansen
authors.forename: Maria
authors.initials: M
authors.lastname: Pedersen
authors.forename: Thomas
authors.initials: T
authors.lastname: Dejgaard
authors.forename: Jakob
authors.initials: J
authors.lastname: Hansen
authors.forename: Gerrit Van
authors.initials: GV
authors.lastname: Hall
authors.forename: Carsten
authors.initials: C
authors.lastname: Thomsen
authors.forename: Thomas P J
authors.initials: TP
authors.lastname: Solomon
authors.forename: Bente Klarlund
authors.initials: BK
authors.lastname: Pedersen
authors.forename: Rikke
authors.initials: R
authors.lastname: Krogh-Madsen
mesh_terms: D052242:Adiponectin / Q000097:blood / Q000502:physiology; D000328:Adult; D001786:Blood Glucose / Q000502:physiology; D001823:Body Composition / Q000502:physiology*; D002149:Energy Intake / Q000502:physiology*; D005951:Glucose Tolerance Test; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D020738:Leptin / Q000097:blood / Q000502:physiology; D008297:Male; D044343:Overnutrition / Q000097:blood / Q000503:physiopathology*; D010101:Oxygen Consumption / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology; D057185:Sedentary Behavior; D016138:Walking / Q000502:physiology*; D055815:Young Adult
chemical_list: D052242:Adiponectin; D001786:Blood Glucose; D020738:Leptin