Any significant weight loss that a previously healthy person has not sought deliberately usually indicates the existence of a systemic disease. Therefore, provided that the clinical examination is performed should ask about weight changes, since a loss of 5% of body weight over a period of six to 12 months requires the immediate execution of further studies.
Physiological regulation of weight The normal individual keeps their body weight at a predetermined level of remarkable stability, given the substantial variations daily caloric intake and activity level. Because of the physiological importance of conserving energy reserves, it is hard to lose weight and keep it off voluntarily. The appetite and metabolism are regulated by a complex network of neural and hormonal factors
The hypothalamic centers of hunger and satiety are essential in these phenomena. Some neuropeptides, such as corticotrophin-releasing hormone (corticotrophin-releasing hormone, CRH), stimulating hormone alpha-melanocyte (α-melanocyte stimulating hormone, α-MSH), and the transcript related to cocaine and amphetamines (cocaine and amphetamine-related transcript, CART) produce anorexia by acting on the central nervous system (CNS) in the centers of satiety.
The ghrelin, glucagon, somatostatin and cholecystokinin are the gastrointestinal peptides which cause satiety and reduce food intake. Hypoglycemia suppresses the action of insulin, which reduces glucose utilization and inhibits the action of the satiety center. Adipose tissue produces lepton and contributes significantly to the preservation of homeostasis weight (long-term) to act in the hypothalamus to reduce food intake and increase energy consumption. Lepton suppresses the expression of hypothalamic neuropeptide Y, which is a powerful stimulant of appetite, and enhances the expression of alpha-melanocyte stimulating hormone, which by means of the melanocortin receptor (MC4R) exerts the effect of mitigating the appetite.