Understanding Why the Obese Can’t Stop Overeating

Hyperphagia breakthrough reveals a defective appetite mechanism in the obese.

Weight loss is a multi-million dollar business. As obesity reaches epidemic proportions, researchers are looking for the key to help obese individuals finally lose weight. While obesity tends to be associated with increased appetite, it can be more of an issue about feeling satisfied when you eat.

Hyperphagia, or excessive appetite, can occur for several reasons; disease, medication or stress. Changes in appetite can ebb and flow, as with anxiety or premenstrual syndrome. On the other hand, the changes can be persistent in nature, as evidenced in diabetes, bulimia or hyperthyroidism.

Increased appetite doesn’t always mean weight gain, although it is true for many individuals. Hyperphagia occurs when obese people consume more food than needed, despite the fact that their bodies have adequate reserves to meet their needs. Those frustrated by overzealous appetites will be glad to know that researchers at the University of Rouen in France have discovered why certain people experience hyperphagia.

The Hunger Hormone

The stomach releases Ghrelin, also known as the “hunger hormone.” It notifies the brain that it’s time to eat. Even though ghrelin levels are generally at normal levels in the obese, their bodies produce antibodies that appear to have a greater attraction to ghrelin than in individuals of a normal weight.

They hypothalamus is the part of the brain that coordinates control of weight and food intake. It adjusts the signals of hunger depending the body’s reserves and physical needs. People who have had a period of increased appetite due to medications, such as corticosteroids, or other events find that their bodies instinctively reduce food intake once the medication is stopped, returning them to their “normal” weights.

overeating breakthrough

Faulty Mechanisms

But in obese individuals, the link between the ghrelin and hypothalamus is defective. Despite diet and exercise, these individuals continue to experience excessive appetite. As a result, they continue to overeat and remain obese or even gain more weight.

The researchers at the University of Rouen found that specific antibodies, called immunoglobulins, identify ghrelin and regulate appetite. Normally, these immunoglobulins bind to ghrelin and allow it to be broken down in the bloodstream. In the obese, this binding action allows the ghrelin to keep acting on the brain, continuing to stimulate appetite.

Researchers discovered that the immunoglobulins have different properties in the obese that in those of normal weight. They have a greater attraction to ghrelin and allow more of it to be transported to the hypothalamus. This allows the brain to continue to stimulate the appetite causing obese people to continue to eat beyond the point that those of normal weight.

To confirm their research, researchers looked at rodents. They administered ghrelin along with immunoglobulins taken from obese individuals. These rodents increased their food intake. In rodents that received only ghrelin or ghrelin combined with immunoglobulins from normal weight individuals, food intake remained at normal levels.

A Clue to a Cure for Hyperphagia

Although the research is still in its early stages, it is a breakthrough in treatment protocol. In the future, physicians will be able to analyze the levels of ghrelin and immunoglobulins in an obese patient’s blood and make changes to the blood chemistry to allow these patients to return to normal appetite levels.

Sources:

http://www.nlm.nih.gov/medlineplus/ency/article/003134.htm

http://www.sciencedaily.com/releases/2013/10/131029133753.htm

http://www.nature.com/ncomms/2013/131025/ncomms3685/full/ncomms3685.html