Obesity May Be Caused By Faulty "Appetite Hormone," Study Finds

obesity
In obese people, glucagon cannot suppress ghrelin, a type of hormone regulating hunger. emilio labrador / Flickr

The appetite hormone glucagon may be to blame for obesity and other weight-related health complication, a new study finds.

Glucagon, which originates in the pancreas, is disseminated throughout the body to trigger the release of stored glucose when blood sugar levels drop. Recently, researchers have begun to suspect that the hormone is also responsible for regulating conscious sensations associated with eating, such as fullness and satisfaction. To do this, glucagon induces the body to adjust the values of hormones like ghrelin, which control feelings of hunger and appetite.

But in obese people, something in this process misfires.

"Once a person becomes obese, glucagon no longer induces feelings of fullness," said lead author Ayman M. Arafat, MD, of Charité-University Medicine in Berlin, Germany. "Further research is needed to determine why glucagon no longer suppresses appetite effectively in this population, even though they are otherwise healthy."

For the study, the researchers enrolled 37 people in an experiment – 11 obese subjects, 13 lean subjects, and 11 type 1 diabetics. After giving the participants either a glucagon or placebo injection, the researchers evaluated the subjects’ sensations of fullness and appetite using a satiety scale and by measuring ghrelin values. They found that within the obese set, the placebo group’s values did not differ from those of the glucagon group.

Conversely, subjects with type 1 diabetes felt significantly fuller after receiving the glucagon shot, and the hormone remained detectable 24 hours after it was administered.

"The findings could influence efforts to develop new treatments for obesity and diabetes," Arafat said. "Although therapeutic agents that influence glucagon and other hormones currently are considered a promising avenue for research, this study suggests a treatment involving glucagon may be ineffective in controlling meal size in people who are obese."

According to the Center for Disease Control and Prevention (CDC), obesity affects one-third of U.S. adults, and has been associated with a heightened risk of developing heart disease, stroke, type 2 diabetes and certain cancers. The agency estimates that the annual medical cost of the epidemic is $147 billion. 

Source: Ayman M. Arafat et al. The Impact of Insulin-independent Glucagon-induced Suppression of Total-Ghrelin on Satiety in Obesity and Type 1 Diabetes MellitusJournal of Clinical Endocrinology & Metabolism, 2013

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