Hunger Hormones: What Is Ghrelin?

  • By: kim
  • Date: June 27, 2021
  • Time to read: 3 min.

The Discovery of Ghrelin

It is quite amazing to think that as recently as 1999 the hormone ghrelin was unknown. It discovered by a researcher called Masayasu Kojima. The name was ghrelin chosen based on it being a “growth hormone-releasing peptide.” If you look at the first letters of the previous quotation, you get “ghre” and “lin”, which is a common suffix for many hormones. As well, “ghre” as the Proto-Indo-European root, translates as “to grow.”

What Is the Hunger Hormone Ghrelin?

It turns out that one of ghrelin role’s is as a hunger stimulator. It is a 28-amino acid hunger stimulating hormone and peptide. When you eat the level of ghrelin decreases and then increases before meals. Even though it has various functions within the body, it has been isolated and recognized as the first circulating hunger hormone.

There are some bariatric operations to treat obesity in which the level of ghrelin is reduced in patients. This helps to cause satiation or the feeling of fullness before it would naturally kick in.

Studies show that ghrelin increases fat mass and food intake by an action that occurs in the hypothalamus within the brain. Cells within the arcuate nucleus, including the orexigenic neuropeptide Y neurons or NPY are activated. The ghrelin response factor of these neurones is insulin sensitive as well as leptin sensitive.

Leptin is the counterpart to ghrelin, in that it is the other hormone that is responsible for making us feel either satiated or hungry.

Does this mean we could develop a vaccine for obesity?

An anti-obesity vaccine has recently been developed which works by targeting the ghrelin hormone. The vaccine utilizes specific antibodies in the immune system to attach to specific targets and ends up directing the body’s immune response against them. This combination of events stops ghrelin from getting to the central nervous system. The result of this process is a reduction in weight gain.

Ghrelin May be Dictating your Food Choices

Studies indicate that having high levels of ghrelin can make junk-food and high calorie snacks seem more appealing. This may be why we choose chocolate or cake over the refrigerator full of fruits and vegetables, more so when we are hungrier. The effect of this hormone is so profound that it mimics a fasting state within the body.

The brain responds with a mild panic response, causing it to target high-energy foods. These are normally the food types which provide more energy than be readily used by the body, and are quickly stored as fat.

This is why there is an increased appetite for high-calorie foods and not low calorie items. Studies show that the brain reward system became more active in patients who were administered ghrelin as compared to those who were not.

How To Keep Your Ghrelin Gremlin Levels Happy

The best way to be proactive with your hunger is to eat small, protein rich meals throughout the day. If you are having something every 2 to 3 hours, you won’t have a chance to become ravenous. By keeping your body eating on a regular basis, the ghrelin levels will not take over and make you want to eat copious amounts of foods. Consuming some protein with every meal will enable you to stay satisfied longer and greatly assist with weight control.


Resources and Further Information

Short sleep duration is associated with high levels of ghrelin and obesity. An inverse relationship between the hours of sleep and blood plasma concentrations of ghrelin exists; as the hours of sleep increase, ghrelin levels trend lower and obesity is less likely…… read more

Eating reduces concentrations of ghrelin. Different nutrients slow down ghrelin release to varying degrees; carbohydrates and proteins restrict the production and release of ghrelin to a greater extent than fats…… read more

The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review.

Leptin and ghrelin are two hormones that have been recognized to have a major influence on energy balance. Leptin is a mediator of long-term regulation of energy balance, suppressing food intake and thereby inducing weight loss. Ghrelin on the other hand is a fast-acting hormone, seemingly playing a role in meal initiation… more


role of ghrelin in weight loss and gain

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