title: Importance of Lean Muscle Maintenance to Improve Insulin Resistance by Body Weight Reduction in Female Patients with Obesity.
abstract: BACKGROUND
  It has recently been suggested that skeletal muscle has an important role in insulin resistance in obesity, in addition to exercise tolerance and the fat index. The aim of this study was to identify body composition factors that contribute to improvement of insulin resistance in female patients with obesity who reduce body weight.
  
  
  METHODS
  We studied 92 female obese patients (age 40.9±10.4 years, body mass index 33.2±4.6 kg/m²) who reduced body weight by ≥5% after an intervention program including diet, exercise therapy, and cognitive behavioral therapy. Before and after the intervention, body composition was evaluated by dual-energy X-ray absorptiometry to examine changes in skeletal muscle mass. Homeostasis model assessment of insulin resistance (HOMA-IR) was measured as an index of insulin resistance. Cardiopulmonary exercise was also performed by all patients.
  
  
  RESULTS
  There were significant improvements in body weight (-10.3%±4.5%), exercise tolerance (anaerobic threshold oxygen uptake 9.1%±18.4%, peak oxygen uptake 11.0%±14.2%), and HOMA-IR (-20.2%±38.3%). Regarding body composition, there were significant decreases in total body fat (-19.3%±9.6%), total fat-free mass (-2.7%±4.3%), and % body fat (-10.1%±7.5%), whereas % skeletal muscle significantly increased (8.9%±7.2%). In stepwise multiple linear regression analysis with change in HOMA-IR as the dependent variable, the change in % skeletal muscle was identified as an independent predictor (β=-0.280, R²=0.068, P<0.01).
  
  
  CONCLUSIONS
  Improvement of insulin resistance in female obese patients requires maintenance of skeletal muscle mass.
authors.affiliation: Department of Health Science, Graduate School of Medicine, Kansai Medical University, Hirakata, Japan. bsk-80@outlook.com.
authors.forename: Yaeko
authors.identifier: http://orcid.org/0000-0001-9677-8762
authors.initials: Y
authors.lastname: Fukushima
authors.affiliation: Department of Health Science, Graduate School of Medicine, Kansai Medical University, Hirakata, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kurose
authors.affiliation: Department of Health Science, Graduate School of Medicine, Kansai Medical University, Hirakata, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Shinno
authors.affiliation: Department of Health Science, Graduate School of Medicine, Kansai Medical University, Hirakata, Japan.
authors.forename: Ha
authors.initials: H
authors.lastname: Cao Thu
authors.affiliation: Department of Health Science, Graduate School of Medicine, Kansai Medical University, Hirakata, Japan.|Health Science Center, Hirakata Hospital, Kansai Medical University, Hirakata, Japan.
authors.forename: Nana
authors.initials: N
authors.lastname: Takao
authors.affiliation: Department of Health Science, Graduate School of Medicine, Kansai Medical University, Hirakata, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Tsutsumi
authors.affiliation: Department of Health Science, Graduate School of Medicine, Kansai Medical University, Hirakata, Japan.|Health Science Center, Hirakata Hospital, Kansai Medical University, Hirakata, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kimura
keywords: Body composition; Body weight loss; Insulin resistance; Lean muscle mass; Obese women