Combining proper nutrition with cardiorespiratory exercise and resistance training can not only help prevent weight gain and other health-related ailments, but also increase energy levels which can offset some of the sedative effects of medications. Cardio exercise increases the heart rate and helps to promote improved cardiac fitness, in addition to burning calories and raising metabolism. Since patients gaining weight often say that they are not eating more, it is tempting to speculate that there may also be a drug-induced lowering of metabolism. Thus, weight gain is due to positive energy balance, which may be explained by an increase in total calories consumed and/or a reduction in calories used by the body. The SSRI medications affect a brain chemical called "Serotonin." The effects of Serotonin on appetite and food intake can be mediated by activation of specific serotonergic receptors (5-HT2C receptors in the hypothalamus). Drugs that block these receptors cause weight gain in both humans and animals, while administration of drugs that stimulate these receptors result in decreased food intake, decreased subjective hunger, and weight loss.
