The human body is a very intricate and complicated instrument. It responds to situations by conveying signals from the hypothalamus and the brain stem which are the control center. When dieting, these signals are generated from the gut, adipose tissue, liver and pancreas. Gut hormones are secreted during the food intake process generating cues, including hunger, satiety, reward and emotional wellbeing. In addition, increased feelings of hunger and decreased feelings of satiety after patients reach their ideal weight are associated with an increase in the 24-hour profile of circulating levels of the "hunger hormone", or ghrelin. These changes in appetite-related hormones may persist for at least 1 year after weight loss and can remain altered indefinitely in a manner that promotes increased energy intake and, ultimately, weight regain. For this reason, successful diet plans include aftercare supervision and support to teach patients how to sustain their new weight over time.