Overdoing the sweets and alcohol this holiday season? Blame your hormones
A hormone produced by the liver controls our appetite for sugar and alcohol, two studies show, suggesting it could be used in therapies to lower our consumption of both after further investigation
If you’re eating too many sweets and downing too many alcoholic drinks this holiday season, blame your hormones. To be specific, blame the lack of a specific hormone which two independent research groups have discovered regulates the intake of sugars and alcohol in mice.
One of the studies found that giving mice the hormone, called FGF21, markedly reduces their preference for sweets and alcohol, and that a single dose of the hormone could cause a monkey to almost immediately lose interest in drinking sweetened water.
FGF21 - or fibroblast growth factor 21 - is a hormone, induced by various metabolic stresses – including ketogenic diets (high in fat, low in carbohydrates, and containing sufficient protein) and high-carbohydrate diets – that keeps the body’s energy supply in balance.
The studies, together with studies of human genetics, show that FGF21 “can exert powerful effects on behaviour by acting on the central nervous system, including in humans”, says Steven Kliewer of the University of Texas Southwestern Medical Centre, a senior author of one of the papers.
Matthew Potthoff of the University of Iowa, a senior author of the other paper, says a lot of work has examined the central mechanisms regulating sugar-seeking behaviour, but the mechanisms regulating the body’s appetite for sugar are poorly understood.
“We never imagined that a circulating, liver-derived factor would exist whose function is to control sweet appetite,” says Potthoff’s co-senior author Matthew Gillum, of the University of Copenhagen. “We are very excited about investigating this hormonal pathway further.”
Studies from over 50 years ago suggested that the liver was an important regulator of food intake and preference. Previous work has also shown that FGF21 is derived primarily from the liver, and that variations in the FGF21 gene sequence are associated with changes in macronutrient preference in humans.
The study from the laboratory of Kliewer and David Mangelsdorf at UT Southwestern and collaborators at Pfizer looked at FGF21 in both mice and monkeys. Kliewer says that while many signalling pathways in the central nervous systems are known to influence the body’s preference for sweets and alcohol, this is the first liver-derived hormone found to have these effects.
The other study, led by Potthoff and Gillum, shows how the hormone works. In mice, the liver produces FGF21 in response to sugar intake. FGF21 then enters the bloodstream and selectively suppresses sugar appetite by acting on the hypothalamus, a part of the brain that regulates food intake and energy balance.
FGF21’s ability to prevent overconsumption of sugar could be harnessed to develop therapies once its effects in humans have been further investigated. But Kliewer cautions: “While at first blush it would seem that this FGF21-regulated pathway could be a panacea for suppressing sugar and alcohol consumption, it’s important to keep in mind that these reward behaviours are closely tied to mood, and so additional studies to determine if FGF21 causes depression are certainly warranted.”