Scientists have identified a liver hormone that suppresses the desire for sugar which may lead to a way to help people beat their sweet tooth.
Research on mice and monkeys has shown that the hormone, FGF21, signals the brain to avoid seeking sweet foods.
Harnessing the effect, possibly by copying the hormone's action with a drug, could help patients who are obese or suffering from Type 2 diabetes, scientists believe.
While certain hormones were already known to regulate appetite, this was the first one specific to sugar consumption.
Dr Matthew Gillum, one of the scientists from the University of Copenhagen in Denmark, said: "We never imagined that a circulating, liver-derived factor would exist whose function is to control sweet appetite.
"We are very excited about investigating this hormonal pathway further."
The study, published in the journal Cell Metabolism, showed that FGF21 exerted a surprisingly powerful effect. In monkeys a single dose caused them to lose interest in sweetened water almost immediately.
Tests in mice revealed that the liver produced the hormone in response to sugar intake.
After entering the bloodstream, FGF21 suppressed sugar appetite by acting on the hypothalamus region of the brain.
The hormone was already known to enhance insulin sensitivity, making it easier for the body to keep blood sugar at a healthy level.
"Now there's this dimension where FGF21 can help people who might not be able to sense when they've had enough sugar, which may contribute to diabetes," said co-author Lucas BonDurant, from the University of Iowa.