The Hormones that Regulate Appetite
There are two Metabolic Hormones Controlling Appetite, Leptin and Grehlin
Leptin:
Discovered in 1994, signals the brain that the body has had enough to eat.
The earliest-discovered of these hormones, and the first hormone ever shown to have a direct role in appetite and weight control. The hormone is secreted in fatty tissue and released into the bloodstream. However, as the amount of fatty tissue in the body increases, the body begins to “resist” the leptin. Obese people often have extremely high levels of leptin circulating in the blood. However, the brain “ignores” the leptin because it has become desensitized to it. For this reason, injecting leptin into obese people to “curb” their appetite has been shown to be ineffective. Also, if obese people reduce fatty tissue by losing weight, it is not clear whether the brain ever recovers its normal sensitivity to leptin.
Conclusion:
Once someone becomes obese and leptin-resistent, automatic self-regulating appetite
control is no longer possible.
Grehlin:
Discovered in 1999, signals the brain to increase feelings of hunger.
Discussion:
Ghrelin is the only major metabolic hormone not secreted in fatty tissue– it is secreted in the lining of the stomach. In obese people, Ghrelin levels tend to be high, increasing the apparent feeling of hunger. Also, Ghrelin levels apparently fail to “cycle” up and down over a 24 hour period, as occurs with thinner people.
Gastric Bypass Surgery and Sleeve Gastrectomy: These types of surgery block part of the stomach, reducing the area of stomach lining being actually used. Because there is less stomach lining, there is less ghrelin being secreted too, resulting in reduced hunger.
Anti-Obesity Vaccine– controlling ghrelin: Scripps Research Institute reported in August 2006 that it had broken through with the first anti-obesity vaccine. Still at a very early stage, Scripps scientists injected mature male rats with a vaccine which acted against ghrelin. The vaccine stimulates the body to produce antibodies which attack or block the ghrelin being secreted.
This finding may be especially important to stop what is commonly known as “yo-yo dieting,” the cycle of repeated loss and regain of weight experienced by many dieters.
These findings may mark a turning point in the treatment of obesity by using the body’s own immune system to combat chronic obesity by the use of targeted antibodies.
No human trials have yet been reported.
