美食的诱惑有多难抗拒?

You might have thought resisting that piece of chocolate cake or extra biscuit was simply a matter of exerting a little will power. But for some of us it’s much more difficult than that – because of the way our brains are wired.

你也许会认为，抵住一块巧克力蛋糕和一块额外的饼干的诱惑，仅仅是发挥一点意志力的问题。但是对我们有些人来说，可没有这么简单，这是因为我们的大脑构造方式不同。

Scientists have found that a key part of the brain which stops the body from acting on impulse – and gorging – does not function as well in those who are overweight or obese.

科学家们近日发现，通常人大脑中阻止身体冲动行事和狼吞虎咽的关键组成部分，却没有办法在超重者或肥胖者的大脑内发生作用。

A study by scientists from Yale University has shown that falling glucose levels lead to a loss of self-control in the brain which subsequently lead to parts of the brain craving high-calorie food such as cakes, biscuits or crisps.

耶鲁大学的科学家们通过研究发现，葡萄糖水平降低会导致大脑自我控制力丧失，这将会造成大脑某些部分对蛋糕、饼干和薯片等高卡路里食物的需求。

In obese people the effect may be even more pronounced, so they are driven to eat by the slightest drop in glucose.

这种影响在肥胖人群身上表现得更为显著，一旦他们的葡萄糖出现轻微降低，他们就会因此开始吃东西。

Glucose is normally obtained from carbohydrate foods, which can come in healthy and less healthy forms.

葡萄糖一般从碳水化合物食物中摄取，可以通过比较健康的方式，也同样有不健康的摄取方式。

Scientists believe the phenomenon occurs because of the brain's huge demand for glucose, which it needs as energy fuel.

科学家认为这种现象的发生是因为大脑对葡萄糖的需求量很大，大脑需要葡萄糖充当能源燃料。

'Good' carbs include fresh fruit and vegetables, brown rice and pasta, nuts, wholemeal bread, and beans.

健康的碳水化合物食物包括：水果，蔬菜，糙米和面食，坚果类，全麦面包和豆类。

Among the 'bad' varieties are white bread, white sugar, biscuits, cakes, crisps and other packet snacks, carbonated soft drinks, ice cream and corn syrup used in processed foods.

列入不健康的碳水化合物名单中的有白面包，白糖，饼干，蛋糕，薯片和其他零食，碳酸饮料，冰激淋和用在加工食品中的玉米糖浆等。

Ensuring adequate brain glucose levels - in a healthy way - might make it easier to stay slim, the research suggests.

研究建议说，能够通过健康的方式为大脑供应充足的葡萄糖可以使保持苗条身材成为比较容易的事情。

“The key seems to be eating healthy foods that maintain glucose levels. The brain needs its food,” said Professor Rajita Sinha, from Yale University in the U.S., who led the study.

研究负责人、来自耶鲁大学的Rajita Sinha教授表示，关键是要通过吃健康的食物来保持体内的血糖水平，我们的大脑需要食物。

The research is reported today in the Journal of Clinical Investigation.

Prof Sinha's team manipulated blood sugar levels in a group of volunteers with intravenous injections of glucose.

该研究今天发表在《临川研究期刊》上，Sinha教授的研究小组通过对一组研究志愿者进行静脉注射葡萄糖来控制他们体内的血糖水平。

At the same time, participants underwent functional magnetic resonance imaging (fMRI) scans of their brains while being shown pictures of high-calorie and low-calorie food, and non-edible items.

同时研究参与者要进行功能性核磁共振检查，来扫描脑部活动。扫描将分别呈现出高卡路里食物、低卡路里食物和非食用性项目的不同结果。

The scans showed that when glucose levels fell, two 'reward' regions of the brain that make certain activities pleasurable induce a desire to eat.

扫描结果显示，当体内葡萄糖水平降低，大脑内的两个“奖励区”会发出一些行动引起进食的欲望。

But the most pronounced reaction was seen in the prefrontal cortex, the 'sensible' part of the brain that prevents people acting on impulse.

最显著的反应出现在前额叶皮层，大脑的“理智”部分将阻止人们冲动行事。

When glucose levels lowered, the prefrontal cortex lost its ability to reign back the urgent 'eat' signals.

当葡萄糖水平降低时，前额叶皮层将失去功能，大脑将会重新执行紧急的“进食”信号。