Insatiable Sweet Tooth? It Might Be Genetic

Isabelle Lucas-Beckett, PhD, Translational Geneticist
Isabelle Lucas-Beckett, PhD
Translational Geneticist

Ever wonder why you just can’t satisfy that sweet tooth? Or why some people can kill a craving with a small piece of chocolate, but you need, well, more than that?

Most people blame their inability to stop eating sugar on willpower, but genetics play a role too. You may actually have a harder time than others tasting the sugar you crave.

The Genetics of Tasting Sugar

DNA gives your body the instructions to make the many thousands of proteins required for just about everything your body needs to do, including tasting sweet and bitter flavors.

TAS1R3 is one of two genes that help your body build the proteins that make up the sweet receptors in your taste buds. Studies show one variant (rs35744813) near this gene can impact how many sweet receptors you have, and thus, how well you can recognize the sweetness in foods.

It all comes down to the T allele. Researchers found that people with one or two copies of the T allele were significantly less able to detect differences in sweetness than people who had two copies of the C allele instead.

Interestingly enough, the T allele is more frequent in people of African descent, whereas the C allele (which is associated with an increased ability to taste sweetness) is more common in people of European descent. One theory is that the ability to taste even small amounts of sugar was critical for survival in colder climates, where most plants did not have high amounts of sugar. After all, we do need some sugar to keep our bodies up and running. In warmer areas, where fruits were plentiful, the ability to taste sugar less would have been less important for survival.

The Sweet Tooth Factor

Now, the big question. Does having this genotype actually give you a sweet tooth? Not necessarily. If you don’t like sweets, not being able to taste them well wouldn’t change that. If you are someone who craves sugar and has a hard time tasting sugar—well, it’s the perfect storm. Your cravings will be harder to satisfy, and thus, you may end up consuming more sugar.

When we looked at data from our members, we found that the number of copies of the T allele is significantly correlated with self-reported sugary beverage consumption. (For reference, 19 percent of Arivale members have one or two copies of the T allele.) When comparing members who say they drink one or more sugary drinks a day and those who drink less than one per day, the T allele is associated with the former.*

Knowing your genetic predisposition could help you understand why your sugar cravings are hard to satisfy. It might also indicate that, for you, it’s especially important to find solutions to avoid going overboard. Knowledge is power, especially when it comes to making difficult changes.

*(p=0.03)