Obesity and the lung: 1. Epidemiology.

Obesity is the most common metabolic disease in the world and its prevalence has been increasing over several decades. The World Health Organization (WHO) predicts that, by 2015, around 700 million adults will be obese (at least 10% of the projected global population). This will be a huge health and economic burden with associated increases in diabetes, cardiovascular and musculoskeletal disease, and malignancy. While there has been little focus on the impact of obesity on respiratory disease, there are clear effects on pulmonary function and inflammation which will increase the prevalence and morbidity of lung disease. There is an inverse relationship between body mass index and forced expiratory volume in 1 s. Increases in body weight lead to worsening of pulmonary function. The reasons for this include the mechanical effects of truncal obesity and the metabolic effects of adipose tissue. Obesity is linked to a wide range of respiratory conditions including chronic obstructive pulmonary disease, asthma, obstructive sleep apnoea, pulmonary embolic disease and aspiration pneumonia. It is important for those providing care for people with respiratory disease to appreciate the impact of obesity and to provide appropriate advice for weight reduction. Healthcare planners should consider the impact of obesity for future resources in respiratory care.