title: Body composition and lung function in cystic fibrosis and their association with adiposity and normal-weight obesity.
abstract: OBJECTIVE
  This study aimed to evaluate the relationship between lung function and body composition in cystic fibrosis (CF) and examine the presence of normal-weight obesity (NWO), a high body fat percentage with a normal body mass index (BMI), in this population.
  
  
  METHODS
  In a pilot, cross-sectional study, 32 subjects with CF and a reference group of 20 adults without CF underwent body composition analysis with air displacement plethysmography. NWO was defined as a BMI <25 kg/m(2) and body fat >30% (for women) or >23% (for men). Lung function in subjects with CF was determined by the percentage of predicted forced expiratory volume in 1 s (FEV1% predicted).
  
  
  RESULTS
  Despite lower BMI and fat-free mass index (P < 0.01), fat mass index and percent body fat did not differ between subjects with CF and the reference group. Among subjects with CF, FEV1% predicted was positively associated with fat-free mass index (β = 6.31 ± 2.93, P = 0.04) and inversely associated with fat mass index (β = -6.44 ± 2.93, P = 0.04), after adjusting for age, sex, and BMI. Ten subjects with CF (31%) had NWO, which corresponded with lower fat-free mass index and FEV1% predicted compared with overweight subjects (P = 0.006 and 0.004, respectively).
  
  
  CONCLUSIONS
  Excess adiposity, particularly in the form of NWO, was inversely associated with lung function in CF. Larger prospective studies should be undertaken to confirm these findings and determine the long-term metabolic and clinical consequences of excess adiposity in CF. As the lifespan of individuals with CF increases, nutrition screening protocols, which primarily rely on BMI, may require reassessment.
authors.affiliation: Division of Endocrinology, Metabolism and Lipids, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA; Center for Clinical and Molecular Nutrition, Emory University School of Medicine, Atlanta, Georgia, USA; Center for Cystic Fibrosis and Airways Disease Research, Children's Healthcare of Atlanta, Atlanta, Georgia, USA. Electronic address: jessica.alvarez@emory.edu.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Alvarez
authors.affiliation: Division of Endocrinology, Metabolism and Lipids, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA; Center for Clinical and Molecular Nutrition, Emory University School of Medicine, Atlanta, Georgia, USA; Center for Cystic Fibrosis and Airways Disease Research, Children's Healthcare of Atlanta, Atlanta, Georgia, USA.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Ziegler
authors.affiliation: Center for Clinical and Molecular Nutrition, Emory University School of Medicine, Atlanta, Georgia, USA; Clinical Research Network, Atlanta Clinical and Translational Science Institute, Atlanta, Georgia, USA.
authors.forename: Erin C
authors.initials: EC
authors.lastname: Millson
authors.affiliation: Center for Cystic Fibrosis and Airways Disease Research, Children's Healthcare of Atlanta, Atlanta, Georgia, USA; Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Arlene A
authors.initials: AA
authors.lastname: Stecenko
mesh_terms: D050154:Adiposity; D000293:Adolescent; D000328:Adult; D001823:Body Composition; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000150:complications / Q000503:physiopathology*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D015596:Nutrition Assessment; D009765:Obesity / Q000150:complications / Q000503:physiopathology*; D050177:Overweight / Q000150:complications / Q000503:physiopathology; D010865:Pilot Projects; D010991:Plethysmography; D055815:Young Adult
keywords: Body composition; Cystic fibrosis; Diet; Lung function; Normal-weight obesity; Obesity