Being Obese Kills Your Taste Buds, And This Is How It Happens

Many studies have shown that our weight is closely linked to how food tastes to us. For instance, one 2016 study revealed how participants who were obese or anorexic had a hard time differentiating regular water and sugar water.

But answers have remained unclear as to why this happened. "We didn't have a good grip on cause and effect," says Robin Dando, assistant professor of food science at Cornell University.

Dando and fellow researchers from Cornell may have found answers after conducting an experiment with several mice, some normal weight, and some overweight. The new study titled 'Inflammation arising from obesity reduces taste bud abundance and inhibits renewal' was published in the journal PLOS Biology on 20 March 2018.

As a part of the experiment, mice were used since their taste buds are similar to that of human beings. One group was fed a regular diet made up of 14% fat and the other group was fed a high-fat diet containing 58% fat. Unsurprisingly, the latter group of mice gained weight due to the nature of their diet. It was soon found that the mice who consumed the high-fat diet had 25% lesser taste buds than the mice who consumed the regular diet. 

Next, two types of mice were fed a high-fat diet. While the first group of regular mice expectedly became obese, the other group of genetically engineered mice did not gain weight no matter what the quantity or type of food they ate. In other words, Dando refers to them as "obesity-resistant". The researchers examined the tongues of the mice and found that both groups had the same number of taste buds.

The two experiments suggested that it was not the diet that affected taste buds but the internal state of being obese. A possible suspect was the obesity-related inflammation, which is induced in the body by a compound called TNF-alpha.

So the researchers decided to look at one more group of mice, this time genetically modified so that they were unable to produce TNF-alpha. The high-fat diet increased the level of TNF-alpha surrounding the taste buds but the mice experienced no reduction in taste buds, despite gaining weight. According to Dando, this demonstrated how the loss of taste buds is actually linked to that inflammatory state. To prove the point further, injecting TNF-alpha directly into the tongue of the mice showed a reduction in taste buds, despite their low level of body fat.

"This could be one potential explanation for why sticking to a diet is so difficult, because you just don't get the taste buds re-establishing fast enough for you to start enjoying your foods with a complete sense of taste," he explained. Given the two-way mechanism, he adds that the loss of taste buds should be reversible.

Further research is required to understand how the inflammation can be dealt with, possibly through therapeutic strategies or a new form of medication to help those diagnosed with eating disorders.