title: The impact of exercise training compared to caloric restriction on hepatic and peripheral insulin resistance in obesity.
abstract: BACKGROUND
  It has been difficult to distinguish the independent effects of caloric restriction versus exercise training on insulin resistance.
  
  
  OBJECTIVE
  Utilizing metabolic feeding and supervised exercise training, we examined the influence of caloric restriction vs. exercise training with and without weight loss on hepatic and peripheral insulin resistance.
  
  
  METHODS
  Thirty-four obese, older subjects were randomized to: caloric restriction with weight loss (CR), exercise training with weight loss (EWL), exercise training without weight loss (EX), or controls. Based on an equivalent caloric deficit in EWL and CR, we induced matched weight loss. Subjects in the EX group received caloric compensation. Combined with [6,6(2)H(2)]glucose, an octreotide, glucagon, multistage insulin infusion was performed to determine suppression of glucose production (SGP) and insulin-stimulated glucose disposal (ISGD). Computed tomography scans were performed to assess changes in fat distribution.
  
  
  RESULTS
  Body weight decreased similarly in EWL and CR, and did not change in EX and controls. The reduction in visceral fat was significantly greater in EWL (-71 +/- 15 cm(2)) compared to CR and EX. The increase in SGP was also almost 3-fold greater (27 +/- 2%) in EWL. EWL and CR promoted similar improvements in ISGD [+2.5 +/- 0.4 and 2.4 +/- 0.9 mg x kg fat-free mass (FFM)(-1) x min(-1)], respectively.
  
  
  CONCLUSIONS
  EWL promoted the most significant reduction in visceral fat and the greatest improvement in SGP. Equivalent increases in ISGD were noted in EWL and CR, whereas EX provided a modest improvement. Based on our results, EWL promoted the optimal intervention-based changes in body fat distribution and systemic insulin resistance.
authors.affiliation: Central Arkansas Veterans Healthcare System, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA. cokerrobert@uams.edu
authors.forename: Robert H
authors.initials: RH
authors.lastname: Coker
authors.forename: Rick H
authors.initials: RH
authors.lastname: Williams
authors.forename: Sophie E
authors.initials: SE
authors.lastname: Yeo
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Kortebein
authors.forename: Don L
authors.initials: DL
authors.lastname: Bodenner
authors.forename: Philip A
authors.initials: PA
authors.lastname: Kern
authors.forename: William J
authors.initials: WJ
authors.lastname: Evans
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001835:Body Weight / Q000502:physiology; D031204:Caloric Restriction / Q000379:methods*; D015444:Exercise / Q000502:physiology*; D008401:Gas Chromatography-Mass Spectrometry; D005934:Glucagon / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008099:Liver / Q000503:physiopathology*; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy / Q000503:physiopathology*; D050177:Overweight / Q000178:diet therapy / Q000503:physiopathology; D018579:Patient Selection; D015431:Weight Loss / Q000502:physiology*
chemical_list: D007328:Insulin; D005934:Glucagon