美食的誘惑有多難抗拒?

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.
你也許會認爲，抵住一塊巧克力蛋糕和一塊額外的餅乾的誘惑，僅僅是發揮一點意志力的問題。但是對我們有些人來說，可沒有這麼簡單，這是因爲我們的大腦構造方式不同。

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.
科學家們近日發現，通常人大腦中阻止身體衝動行事和狼吞虎嚥的關鍵組成部分，卻沒有辦法在超重者或肥胖者的大腦內發生作用。

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.
耶魯大學的科學家們通過研究發現，葡萄糖水平降低會導致大腦自我控制力喪失，這將會造成大腦某些部分對蛋糕、餅乾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.
這種影響在肥胖人羣身上表現得更爲顯著，一旦他們的葡萄糖出現輕微降低，他們就會因此開始吃東西。

Glucose is normally obtained from carbohydrate foods, which can come in healthy and less healthy forms.
葡萄糖一般從碳水化合物食物中攝取，可以通過比較健康的方式，也同樣有不健康的攝取方式。

Scientists believe the phenomenon occurs because of the brain's huge demand for glucose, which it needs as energy fuel.
科學家認爲這種現象的發生是因爲大腦對葡萄糖的需求量很大，大腦需要葡萄糖充當能源燃料。

'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，糙米和麪食，堅果類，全麥麪包和豆類。

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單中的有白麪包，白糖，餅乾，蛋糕，薯片和其他零食，碳酸飲料，冰激淋和用在加工食品中的玉米糖漿等。

Ensuring adequate brain glucose levels - in a healthy way - might make it easier to stay slim, the research suggests.
研究建議說，能夠通過健康的方式爲大腦供應充足的葡萄糖可以使保持苗條身材成爲比較容易的事情。

“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.
研究負責人、來自耶魯大學的Rajita Sinha教授表示，關鍵是要通過吃健康的食物來保持體內的血糖水平，我們的大腦需要食物。

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.
該研究今天發表在《臨川研究期刊》上，Sinha教授的研究小組通過對一組研究志願者進行靜脈注射葡萄糖來控制他們體內的血糖水平。

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.
同時研究參與者要進行功能性核磁共振檢查，來掃描腦部活動。掃描將分別呈現出高卡路里食物、低卡路里食物和非食用性項目的不同結果。

The scans showed that when glucose levels fell, two 'reward' regions of the brain that make certain activities pleasurable induce a desire to eat.
掃描結果顯示，當體內葡萄糖水平降低，大腦內的兩個“獎勵區”會發出一些行動引起進食的慾望。

But the most pronounced reaction was seen in the prefrontal cortex, the 'sensible' part of the brain that prevents people acting on impulse.
最顯著的反應出現在前額葉皮層，大腦的“理智”部分將阻止人們衝動行事。

When glucose levels lowered, the prefrontal cortex lost its ability to reign back the urgent 'eat' signals.
當葡萄糖水平降低時，前額葉皮層將失去功能，大腦將會重新執行緊急的“進食”信號。