Hope for Overeaters? Feeling Full May Have a Chemical 'Switch'

A man eating a burger.
(Image credit: Odua Images)

It may be possible to flip a chemical "switch" to turn on a feeling of fullness, a new study in mice suggests.

In the study, researchers found that a certain enzyme plays a role in how the brain responds to the hormone leptin, which normally signals that the body has consumed enough food and we should stop eating, according to the study, published in the journal Nature Communications on Monday (Feb. 29).

Leptin is a hormone that is released by fat tissue and binds to leptin receptors in the brain. Too much leptin, however, can lead to a condition called leptin resistance, in which the brain stops responding to leptin and therefore doesn't receive the signal to stop eating.  [8 Tips for Fighting Sugar Cravings]

Because leptin is secreted by fat tissue, the more fat tissue a person has, the more leptin is secreted. As a result, leptin resistance is common in obese individuals.

But enzymes in the body also appear to play a role in leptin resistance.

In the new study, the researchers found that an enzyme, called HDAC5, plays a role in the leptin pathway, according to the study. 

In the study, mice that could not make this enzyme were resistant to leptin, while mice that produced an excess of the enzyme were more sensitive to leptin. In addition, the researchers found that excess levels of the enzyme appeared to have a protective effect — that is, the mice with high levels of the enzyme did not gain as much weight as expected when fed a high-fat diet. 

More research is needed — whether the enzyme works the same way in humans is unclear.

But restoring "leptin sensitivity is an important step on the path towards sustainable weight loss and towards combating" diseases that can result from obesity such as Type 2 diabetes, Paul Pfluger, a neurobiologist at the Helmholtz Center Munich, a German Research Center for Environmental Health, said in a statement.

"In addition to the essential changes in diet and exercise behavior, in the future the individual components of the leptin [pathway] could be potential drug targets to support the weight loss process," Pfluger said.

However, he noted that it remains to be seen whether the enzyme will be a suitable target for fighting obesity in humans.

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Sara G. Miller
Staff Writer
Sara is a staff writer for Live Science, covering health. She grew up outside of Philadelphia and studied biology at Hamilton College in upstate New York. When she's not writing, she can be found at the library, checking out a big stack of books.