It’s been known for decades that the liver helps to regulate sugar intake. But researchers have recently discovered the organ’s secret weapon in the battle against sweets: a hormone called fibroblast growth factor 21 (FGF21).

Residing in the liver, FGF21 communicates with the brain when you’ve had enough sugar. According to the research revealed on Dec. 24, the hormone tells the brain to cut off the sweet tooth with a simple signal that says, “I’m full and satisfied—no more sugar, please.”

This is the first time a single mechanism has been found in the liver that puts the brakes on cravings. The hormone simply “shuts off that reward pathway,” says Matthew Potthoff, an assistant professor of pharmacology at the University of Iowa and co-author of the study which will be published in the journal Cell Metabolism in February 2016.

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Researchers figured out the effects of FGF21 by pumping up its levels in some of their lab mice. They found that the mice with extra FGF21 preferred a standard ‘mice chow’ diet over a sugary one. But the mice with regular FGF21 levels couldn’t resist the sugar kick when offered. Since the hormone has been proven to work the same way in humans, the researchers think this new finding could unlock drug therapies that can curb human addictions to sweets among other things.

The University of Iowa research is part of a growing field of research into how the body could better coach itself to eat better. And the sugar hormone may not be the only one that could help regulate how and what people are eating. Last year, a research team out of Imperial College London discovered it might be possible to create a ‘diet pill’ to combat obesity by adding more fiber into the gut. Their initial trials were successful at stopping weight gain in overweight adults. Other new research out of Philadelphia’s Monell Chemical Senses Center suggests some kids are genetically predisposed to sugar—they have a stronger ‘sweets signal’ and could have stronger cravings for sweet foods, especially when they’re restricted.

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The next step, says Potthoff, is to determine if there are other similar hormones that regulate things like fat and protein intake. By testing the hormones on more of those pathways, there could be more therapies in store, not just for blocking people’s food cravings, but also for targeting other health challenges like drug addiction and diabetes.

But it will likely be years before these findings become actual therapies. Luckily, blocking the sugar hormone isn’t the only way to fight food cravings. Willpower will also help you slow down your holiday cookie tin binge.