Thursday, December 22, 2011
Weight management is used to be considered a simple matter of willpower: you versus food. Now researchers understand that controlling body weight is a complex process influenced by genes and regulated by the brain.
The body produces a protein called leptin that is made in fat cells. Leptin causes to decrease appetites and increase metabolism, causing weight loss.
Because humans produce leptin, researchers hoped giving the hormone to obese people would result in weight loss. However, leptin did not turn out to be the amazing cure-all for which scientists, physicians, and patients had hoped.
Brain researchers continued to look for molecules that, like Leptin, control food intake. What they found was a complex system of chemicals and genes that tightly control appetite and weight.
Hypothalamic neuropeptides, orexin-A and orexin-B, suggested an important role in appetite regulation. Quite extensive literature on orexins and appetite control, although the evidence for orexin (particularly orexin-A and the orexin-1 receptor) involvement in many aspects of ingestive physiology and behavior is unquestionable. Since the orexin system is selectively activated by signals indicating severe nutritional depletion, it would be highly adaptive for a hungry animal not only to seek sustenance but also to remain fully alert to dangers in the environment. Crucial evidence indicates that orexin-A increases food intake by delaying the onset of a behaviorally normal satiety sequence.
Ghrelin – low levels of glycogen and low blood sugar levels stimulate a production of ghrelin and Neuropeptide Y (NP Y) activity in the hypothalamus. As NPY is stimulated, you will crave for sweet and starchy foods. And when ghrelin rises, appetite is stimulated.
While you are asleep, your glycogen and blood sugar stores are used up, causing the brain to release NPY. Skipping breakfast increases NPY levels so that by afternoon, you’re set up for a carbohydrate binge. This craving for carbohydrate is not the result of a lack of willpower; it is a physiological requirement at work.
Galanin is released when fat stores needs to be restored. In the evening, galanin levels tend to increase, which may be our body’s way of making sure that people have sufficient calories to last them through the night. Chronically elevated Galanin may regulate body weight, metabolic rate, and lipid and carbohydrate metabolism through a mechanism that is independent of feeding regulation.
Posted by Niño Mahilum