Do you have a sweet tooth? It could be your liver!


For many of us, avoiding sweet foods in order to lose weight is a big ask! But could having a sweet tooth be less about behaviour and more about our biology? Researchers are starting to believe so!

In the past, animal studies have suggested that a hormone produced by the liver appeared to suppress the desire to eat sweet foods. Researchers decided to look to see whether this same effect occurred in monkeys – and found exactly the same hormone having exactly the same effect.

The next obvious step was to look at us humans! Danish researchers found that people with a FGF21 variant, a gene responsible for how much FGF21 hormone we have in our blood, were more likely to have a sweet tooth.

The more FGF21 we have in our blood, the less likely we’re inclined to eat sweet foods. In fact, after a period of fasting, the study found that FGF21 levels in the blood were much higher in those people who did not like sweet foods than among those who did. FGF21 response to sugar, however, was the same among everyone.

Therefore, the amount of FGF21 we carry in our blood appears to correlate with our desire for sweet foods. In fact, lacking this hormone appears to generate a preference for carbohydrates overall, and less desire for proteins and fats.It’s possible, therefore, that this hormone’s overall responsibility is the regulation of the macronutrients we consume in our diet, although more studies are required to clarify this.

So if you have a sweet tooth, it’s possible that you lack the FGF21 hormone!

The implications of this study are potential door-openers for other fields of research into obesity and diabetes. Both of which are increasing rapidly in many countries. It’s becoming evident that these metabolic diseases have many causes and associations, and the more that is discovered, the more complex these conditions appear.

Researchers are accepting that there could well be biological as well as behavioural reasons for why some people put on weight and why some struggle to lose it.

The study

Søberg et al (2017) FGF21 is a sugar-induced hormone associated with sweet intake and preference in humans. Cell Metabolism 25, 1045-1053

So what do you think?

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