The Appetite Control Center
The appetite control center is housed in a part of the brain called the hypothalamus. There are many hormones that affect it; here are the most important ones.
Ghrelin
Ghrelin stimulates appetite. It’s released when the stomach is empty, and its released stops when we eat. Carbohydrates and protein appear to suppress this appetite stimulating hormone more than fat does, which seems to be one of the reason that high fat diets promote weight gain.
Leptin
Leptin, insulin and amylin work together to reduce appetite. Both leptin and insulin dampen appetite by inhibiting neurons in the appetite control center that stimulate appetite and by stimulating neurons that depress appetite.
Leptin is released from fat tissue, and as the amount of body fat grows leptin levels also increase. It would be logical to assume this would work to the advantage of people who are obese, as leptin reduce appetite.
However research suggests that the appetite control center becomes resistant to leptin when levels are unusually high over time.
Consequently, leptin would be less efficient at suppressing hunger. Weight loss helps to reduce body fat and leptin secretion; it helps to restore leptin sensitivity.
Insulin
The story for insulin is strikingly similar. Insulin is released by the pancreas. As body fat increases, the risk of insulin resistance also increases ( a condition in which the body fails to use insulin properly).
The pancreas pumps out even more insulin, in effort to compensate. Not surprisingly, when the body becomes resistant to insulin, the appetite control center also becomes resistant to insulin.
With increasing weight gain, a vicious cycle is set in motion; appetite control is lost energy expenditure slows down, and eating increases.
As is the case with leptin, weight loss helps to decrease insulin secretion and restore insulin sensitivity.
Amylin
Amylin is secreted along with insulin from the pancreas. This hormone works together with insulin to slow emptying of the stomach. Amylin reduces hunger and helps to control body weight.
All in all, overweight and obesity seem to upset the delicate balance of appetite control hormones, Fortunately with a healthful lifestyle and weight loss, this balance can be restored.
The Appetite Control Center
