Scientists say the findings could help devise new approaches to losing weight, with a greater focus on taste perception.
Obesity dulls the sense of taste, according to research that offers new insights into why some people enter a persistent cycle of weight gain.
Researchers found that within eight weeks of becoming obese, mice lost 25% of their taste buds. The findings suggest that weight gain not only changes appetite but may also fundamentally alter the way taste is perceived.
“Obesity is by nature very complex,” said Robin Dando, a food scientist at Cornell University in New York and senior author. “There are a bunch of different factors that contribute to our state of obesity – we think a change to taste is one of those, and one that people don’t tend to consider.”
The findings are the latest to push back against the assumption that people become obese because they love food more than the average person and so find it harder to resist. “I think liking food more may not be what’s going on,” said Dando.
Several converging lines of evidence now suggest the reverse may be true. Studies of brain activity have found that people with higher body mass index appear to find pleasant tastes relatively less rewarding – as measured by their brain response – and so may need to eat more to obtain the same dopamine kick. Other work has shown that people with dulled taste sensitivity tend to gravitate towards sweeter, fattier foods.
In the study, the mice were fed either a normal or a fatty diet. After eight weeks, the mice on the high-fat diet weighed about one third more. The scientists found they also had about 25% fewer taste buds than the lean mice.
Taste buds comprise about 50 to 100 cells of three major types, with different roles in sensing the five primary tastes (salt, sweet, bitter, sour and umami). These cells have a rapid turnover, living an average of just 10 days.
Nicola Pirastu, a geneticist who works on food preference at the University of Edinburgh, said the findings suggest obesity may exaggerate underlying differences in taste perception that incline people towards unhealthy food choices in the first place.
“If we were to translate this to humans who can choose their food, this could push people to look for even more calorie-dense food,” he said. “This could create a feedback loop in which lower taste buds would increase obesity, which would reduce the number of taste buds, thus increasing obesity even more.”
Dando said the findings could help devise new approaches to losing weight, with a greater focus on the influence of taste perception on what people eat.