The aging lung is characterized by changes that result in both loss of elasticity and muscle strength, causing alterations in lung volumes, such as decreased vital capacity. Obesity compounds these changes. Fat accumulates around the ribs and diaphragm, and there is increased inspiratory resistance and loss of chest wall compliance. This causes an increased work of breathing which, in the worst case, can lead to dyspnea. There is not a clear-cut relationship between parameters of body weight and mass and alterations in pulmonary function, but loss of expiratory reserve volume, functional residual capacity, forced expiratory volume and forced vital capacity have been described. Dieting can improve pulmonary function, but undernutrtion must be avoided.