What is ghrelin, the hunger hormone, used for?
A leptin antagonist hormone, ghrelin mainly sends hunger signals to the brain to promote food absorption. However, it can be problematic in the event of a malfunction.
What is ghrelin?
Ghrelinis a hormone produced by the stomach and pancreas thatstimulates appetite. It is antagonistic toleptin, which has the role of controlling the satiety effect of the body, but the two hormones act in a complementary way to regulate the weight of an individual(1). This molecule is also called the “hunger hormone” and is of paramount importance.
When it works normally, it is found at a high level just before meals, but its level should drop as the stomach fills up and leptin levels rise.
In subjects who do not have any dysfunction in hormone levels, they work in a complementary way. After too high a level of feeding for a while, most individuals will tend to naturally regulate the amount of food swallowed to regulate their weight. But some dysfunctions can disrupt this regulatory system andlead to obesity.
Ghrelin dysfunction in obese subjects
The causes of obesity cannot always be identified. However, in some cases, hormonal or physiologicaldysfunctionmay be involved. A 2013 study found that specific antibodies were found in obese patients with normal ghrelin levels(2).
This study showed that these immunoglobulins had the ability to recognize a hunger hormone but protected it instead of promoting its rapid breakdown in the blood. Thus, a larger amount can be transported to the brain and inhibits the action of the satiety hormone. It is this dysfunction that results in some cases ofovereating .
In some people, we can also witness an increase in the level of the hormone. This is particularly the case in children withPrader-Willi syndrome (3), a disease that causes a deficit of growth hormone and very significant hyperphagia causing childhood obesitytag. But, ghrelin can also be present in abnormal quantities in patients suffering from anorexia nervosa. In this case, she is only present to try to correct the situation.
The influence of ghrelin on the brain
During a normal day, ghrelin is produced in sufficient quantities and brought to the brain. Neurons then send signals to the hypothalamus to encourage the ingestion of food. The action of the hormone is then compensated by other mechanisms that interact with the brain to establish thefeeling of satiety .
The hunger hormone is very sensitive to external dysfunctions. The presence of antibodies can alter the quantity, as can external environmental factors. However, depending on the quantity of hormones sent to the brain, the hypothalamus will react differently by secreting various molecules. Among them, we find in particular orexin, which is a molecule that promotes excessive eating behavior, mainly hyperphagia.
The strong influence of this hunger hormone on the brain has consequences for how you gain or lose weight. Once the problem has been identified, certain diets must absolutely be avoided to promote the recovery of a normal weight. However, many fad diets work against sustained weight loss in the context of hormonal dysfunction.
How does the hunger hormone change during a diet?
For several years, a team working at the University of Southern California studied the evolution of ghrelin levelsin the body at different stages of a diet (4). The main information that emerges from this study is the significant increase in hunger hormone levels after a period of fasting that is a little too long.
The team conducted their experiment on rats that were only allowed to eat for a period of four hours, with an obligation to fast for the rest of the day. After fasting, when food was perceived by the rat, the hormone was sent to the brain, where the hypothalamus produced large quantities of orexin, promoting excess food intake.
This mechanism has a significant utility in times of scarcity by allowing the body to absorb an abnormal number of calories over a given period to cope with a fast. But with the abundance of food, this mechanism has become a problem for some people. This is also the reason why it is strongly discouraged to follow a diet involving excessive fasting if you want to lose weight in the long term.
Stephen Paul is the lead author and founder of My Health Sponsor. Holder of a diploma in health and well-being coaching with more than 200 articles in the field of health, he makes it a point of honor to offer advice based on reliable information, based on scientific research, and verified by health professionals.