This review focuses on nutritional abnormalities, one of the most prominent extrapulmonary manifestations occurring in chronic obstructive pulmonary disease (COPD). Diagnosis is usually made by either anthropometry or determination of body composition. Deficiencies in nutritional status, such as body weight and muscle mass loss, are the result of an interaction of several factors, including the imbalance between energy supply and requirements, tobacco, low physical activity, and systemic inflammation. These factors essentially determine the predominance of protein breakdown over synthesis. The loss of body weight and lean mass leads to muscle dysfunction and exercise limitation, also having a negative impact on exacerbations and mortality. Therapies include changes in lifestyle and nutritional supplements. Anabolic drugs may be administered in some cases. Obesity is also very prevalent in COPD patients, being associated with cardiovascular and metabolic comorbidities. Although, paradoxically, moderate obesity appears to reduce mortality, healthy lifestyle habits are recommended to avoid morbid obesity. (BRN Rev. 2017;3:56-71)