Scientists appear to have found an answer to the question of why people’s sense of taste appears to become duller as they gain weight.
Robin Dando, an assistant professor of food science at Cornell University, experimented on mice to find out why this phenomenon occurs. He and graduate students Andrew Kaufman and Ezen Choo gave several mice a special diet designed to fatten them up. Eight weeks after, the rodents were euthanized so that their tongues could be examined and compared to skinnier mice, NPR reports.
Doctors have known about this characteristic of taste buds for the past few years, after studies showed that obese people perform less ably on taste tests compared to people of normal weight. Dando said,
We didn’t have a good grip on cause and effect.
For example, does eating too much heavy foods dull the tongue’s sensitivity to taste more flavors? Or is excess body fat the culprit?
Looking at the tongues of the mice, Dando found that the taste buds were withering in those of the fat mice. “The obese ones have about 25 percent fewer taste buds,” he said. Since taste buds are made of around a hundred cells, when mice got fat, the older cells started dying off more quickly and getting replaced with newer, younger cells more slowly.
The researchers had two more groups of mice for the experiment. One was made up of genetically-engineered rodents that were “obesity-resistant.” They were given the same diets as the fat mice, but did not gain weight. On examination, their tongues showed a normal number of taste buds, meaning the dulling of taste is not because of diet, Dando explained.
Then the team looked at another group of mice that could not produce a molecule called TNF alpha – a compound that allows inflammation in the human body. these molecules are naturally higher in obese people, causing them to have more inflammation. But when these particular mice got fatter, they likewise showed the same number of taste buds.
On the bright side, taste buds do come back. “This is a two-way mechanism. Probably the opposite happens,” Dando said.
The study was published in PLoS Biology.