OBSTRUCTIVE, OCCUPATIONAL AND ENVIRONMENTAL DISEASES: Edited by Manish Joshi and Basil VarkeyImpact of obesity on pulmonary function: current understanding and knowledge gapsHegewald, Matthew J.a,bAuthor Information aDivision of Pulmonary and Critical Care Medicine, Intermountain Medical Center, Murray bDivision of Respiratory, Critical Care, & Occupational Pulmonary Medicine, University of Utah, Salt Lake City, Utah, USA Correspondence to Matthew J. Hegewald, MD, Intermountain Medical Center, Division of Pulmonary & Critical Care Medicine, Sorensen Heart-Lung Center, 6th Floor, 5121 South Cottonwood Street, Murray, UT 84107, USA. Tel: +1 801 507 4870, fax: +1 801 507 4792; e-mail: [email protected] Current Opinion in Pulmonary Medicine: March 2021 - Volume 27 - Issue 2 - p 132-140 doi: 10.1097/MCP.0000000000000754 Buy Metrics Abstract Purpose of review Obesity is an increasing world-wide public health concern. Obesity both causes respiratory symptoms and contributes to many cardiorespiratory diseases. The effects of obesity on commonly used lung function tests are reviewed. Recent findings The effects of obesity on lung function are attributed both to mechanical factors and to complex metabolic effects that contribute to a pro-inflammatory state. The effects of obesity on lung function correlate with BMI and correlate even better when the distribution of excess adipose tissue is taken into account, with central obesity associated with more prominent abnormalities. Obesity is associated with marked decreases in expiratory reserve volume and functional residual capacity. Total lung capacity, residual volume, and spirometry are less affected by obesity and are generally within the normal range except with severe obesity. Obesity decreases total respiratory system compliance primarily because of decreased lung compliance, with only mild effects on chest wall compliance. Obesity is associated with impaired gas transfer with decreases in oxygenation and varied but usually mild effects on diffusing capacity for carbon monoxide, while the carbon monoxide transfer coefficient is often increased. Summary Obesity has significant effects on lung function. The relative contribution of the mechanical effects of obesity and the production of inflammatory cytokines by adipose tissue on lung function needs further study. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.