As epidemics go, obesity looks like it is here to stay. The weight loss industry is counted in the billions of dollars. The most common pulmonary complaint of obese patients is shortness of breath with activity (exertional dyspnea). Obesity influences breathing patterns, called respiratory mechanics, and metabolic rate. A low oxygen level can also be a manifestation of obesity. The exact reason this occurs is not totally clear.

Hypoxia, which is the medical term for a low oxygen level, may occur for at least 3 reasons in the obese patient: first, obese patients can have the so-called “obesityhypoventilation syndrome”, which occurs when obese patients cannot exhale all of the carbon dioxide in their breathing; second, many obese patients have co-morbidities, such as heart failure; and the third reason is more difficult to explain but here goes. Obesity can actually affect your lung volumes. The exact volumes and how they are measured are too complex for a discussion here, but involve calculating something called the closing capacity. The bottom line for all of this is that obesity can cause a reduction in blood oxygen levels.

Unfortunately, it does not do it consistently. This means that pulmonary function studies and measurements of blood oxygen levels are important. It should come as no surprise that the treatment for obesity patients is oxygen, when needed, and a firm commitment to weight loss. Weight loss is difficult, but the benefits, not only to pulmonary health, but to health in general, make it a priority.