Body composition and lung function in cystic fibrosis and their association with adiposity and normal-weight obesity

• Published in: Nutrition (Burbank, Los Angeles County, Calif.) Vol. 32; no. 4; pp. 447 - 452
• Main Authors: Alvarez, Jessica A., Ziegler, Thomas R., Millson, Erin C., Stecenko, Arlene A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2016; Elsevier Limited
• Subjects: Adiposity; Adolescent; Adult; adults; Body Composition; Body Mass Index; Chronic illnesses; Cross-Sectional Studies; Cystic fibrosis; Cystic Fibrosis - complications; Cystic Fibrosis - physiopathology; densitometry; Diet; fat mass index; Female; Forced Expiratory Volume; Gastroenterology and Hepatology; Humans; lean body mass; longevity; Lung - physiopathology; Lung function; Male; men; Normal-weight obesity; Nutrition Assessment; Obesity; Obesity - complications; Obesity - physiopathology; Overweight - complications; Overweight - physiopathology; Pilot Projects; Plethysmography; prospective studies; protocols; Respiratory function; screening; Teenagers; women; Young Adult; Obesity; Cystic fibrosis; Normal-weight obesity; Lung function; Diet; Body composition
• ISSN: 0899-9007; 1873-1244
• DOI: 10.1016/j.nut.2015.10.012

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. 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/m2 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). 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). 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. •Fat-free mass was positively associated with lung function in cystic fibrosis (CF).•Adiposity in subjects with CF was inversely associated with lung function.•Thirty percent of subjects with CF had normal-weight obesity (NWO).•Subjects with CF and NWO had reduced fat-free mass and reduced lung function.•Nutrition screening protocols that primarily rely on body mass index may require reassessment.