Previous studies in mice and non-human primates have suggested that a liver hormone encoded by the gene FGF21 drives feeding behaviour. To study the effects of the gene in humans, Matthew Gillum and Niels Grarup at the University of Copenhagen and their colleagues analysed its sequence in a cohort of more than 6,000 people and looked for associations with individuals’ reported frequency of eating certain sweet foods, such as confectionery and cake. They found links between specific gene variants and higher sugar consumption; the strongest association was with snacking on sweets.
A separate experiment on 51 volunteers showed that, after 12 hours of fasting, blood levels of FGF21 were higher in those who said they disliked sweet foods. In all cases, levels increased after people ate sugar. The findings suggest that the hormone regulates cravings for and intake of sweets.