Obesity¹ dulls the sense of taste, according to research that offers new insights into why some people enter a persistent² cycle of weight gain.

最新研究显示，肥胖会让味觉变得迟钝。这一发现对于了解为什么有些人会陷入体重增加的不断循环提供了新的思路。

Researchers found that within eight weeks of becoming obese³, 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.

研究人员发现，老鼠在变得肥胖的8周内失去了25%的味蕾。该发现表明，体重增加不仅会改变食欲，也可能从根本上改变味觉。

"Obesity is by nature very complex," said Robin⁴ 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."

美国康奈尔大学的食物专家罗宾·丹多称：“肥胖从本质上说是非常复杂的。造成肥胖的因素很多--我们认为味觉的改变是其中之一，也是人们往往忽视的一个因素。”

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 liking⁵ food more may not be what's going on," said Dando.

有观点认为，人们之所以变胖是因为他们比一般人更爱吃，更难抵御吃的诱惑。上述研究发现是反驳该观点的最新例证。丹多说：“我认为更爱吃可能不是真正的原因。”

Several converging⁶ lines of evidence now suggest the reverse may be true.

几条综合证据表明，情况可能恰恰相反。

Studies of brain activity have found that people with higher body mass index appear to find pleasant tastes relatively⁷ less rewarding -- as measured by their brain response -- and so may need to eat more to obtain the same dopamine kick.

对大脑活动的研究发现，身体质量指数较高的人似乎会觉得美味只能带来相对较少的奖励--根据他们的大脑反应来衡量--因此可能需要吃得更多才能获得同样水平的多巴胺。

Other work has shown that people with dulled taste sensitivity tend to gravitate towards sweeter, fattier foods.

其他的研究表明，对味觉迟钝的人倾向于吃更甜、更油腻的食物。

The latest findings suggest obesity does not simply reprogramme taste perception at the psychological level.

最新研究证实，肥胖并不只是简单地在心理层面上改变味觉。

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.

在这项研究中，老鼠被分成两组，分别喂食正常的食物或油腻的食物。8周后，吃高脂肪食物的老鼠的体重比吃正常食物的老鼠重了大约三分之一。科学家还发现，它们的味蕾比瘦老鼠少了大约25%。

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 turnover⁸, living an average of just 10 days.

味蕾由三大类大约50至100个细胞组成，在感知五味（咸、甜、苦、酸和鲜）时起着不同作用。这些细胞更新迅速，平均寿命仅10天。

The findings suggest taste buds and their progenitor⁹ cells are particularly sensitive to damage from inflammatory chemicals that are raised in obesity, resulting in a rapid decline of the overall number.

该研究发现，味蕾及其其祖细胞对于肥胖时增多的炎性化学物质的危害特别敏感，造成整体数量迅速减少。

The study homed in on one specific inflammatory chemical that is elevated in obesity, called TNF-alpha, which acts as a messenger between the body's cells.

研究锁定一种在肥胖时增多的炎性化学物质，它被称为肿瘤坏死因子（TNF-alpha），充当的是体细胞之间的信使。

The scientists found that mice that had been engineered to be genetically¹⁰ incapable¹¹ of making TNF-alpha did not experience any reduction in taste buds, despite gaining weight, suggesting this compound may be the culprit.

科学家发现，经改造后使其基因没有能力制造TNF-alpha的老鼠，尽管体重增加，但是味蕾并没有减少，表明这种化合物可能就是罪魁祸首。

The team now plan to assess whether the same process occurs in people. "We're certainly not identical to mice in our physiology¹², but our taste buds work pretty similarly, and the same factors related to inflammation we think are responsible for taste loss are elevated when we become obese," said Dando.

该研究小组现在计划评估人体是否会发生同样的情况。丹多说：“从生理上讲，我们当然跟老鼠不一样。但是我们的味蕾作用很相似，我们认为跟炎症有关的造成味觉丧失的同样的因子在我们变肥胖时会增多。”

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.

丹多称，这些研究结果可能有助于找到新的减肥方法，这些方法会更重视味觉对人们进食的东西的影响。