Obesity results from an imbalance between caloric consumption and caloric expenditure over a prolonged period. Weight gain occurs when there is a greater consumption of calories than expenditure. The expenditure of calories is complex and results from likely combinations of metabolic, genetic, and individual factors. Genetics and environment may predispose to weight gain, but it is only the consumption of calories in excess of utilization that can cause weight gain. (more…)

In elderly people there is a notable reduction in the capacity to produce new blood cells. Yet, unless there is substantial physiological stress, the number of circulating cells remains fairly constant. Quantitative deficiencies are only apparent when stress produces a demand that exceeds reserve proliferative capacity. Such a demand might occur during an acute infection or after cytotoxic chemotherapy. (more…)