This new edition provides a fully updated guide to obesity’s relation to lung disease. Over forty percent of the U.S. population is obese, and obesity is increasing in much of the world. Obesity has a major impact on health conditions such as diabetes and cardiovascular disease. The effects of obesity on lung disease have drawn increasing attention in recent years. Furthermore, the COVID pandemic has dramatically illustrated how obesity affects respiratory disease, constitutes a major risk factor for COVID-19, and presents challenges to pulmonary care in the ICU. Obesity changes physiology, immune and metabolic function, and is associated with changes in diet and the microbiome, all of which combine to have a major impact on the pathogenesis of respiratory diseases. Obesity is thus a risk factor for many respiratory diseases such as asthma, pulmonary hypertension, thromboembolic disease, obstructive sleep apnea and ARDS. Obesity also complicates the management of manyother respiratory diseases and conditions such as COPD, thromboembolic disease, and the care of the critically ill patient.The objectives of this book are three-fold:  To review how physiological, immune and metabolic factors might contribute to lung disease.  To discuss the impact of obesity on common lung diseases To outline important considerations in the management of critically ill obese patients. There have been major advances in our understanding of the relationship between obesity and lung disease since the first edition in 2013, in addition to the major lessons learned about the importance of obesity during the COVID-19 pandemic. This has led to the addition of eight new chapters on topics such as, the microbiome, lung transplant, and COVID-19 in the ICU. This is an ideal guide for all clinicians taking care of patients with pulmonary and critical care diseases, as well as basic and translational scientists interested in how obesity affects respiratory health.