爲什麼你明明不餓，卻總想吃東西？科學解釋來了！
Have you ever wondered why some days all you want to do is snack?
不知道你有沒有想過這個問題：爲什麼有時候你會不停地想吃東西？
Under normal circumstances, we feel hungry when we have burnt up the food we have eaten as energy and our blood sugar and insulin levels begin to drop. Ghrelin, a hormone connected to appetite, then communicates this to the brain, which is how we feel the need to eat.
在正常情況下，當身體把食物轉爲能量消耗掉之後，我們的血糖和胰島素水平也開始降低，這時我們就會感到飢餓。然後，飢餓激素將這個信息傳達給大腦。這樣我們就會感覺到需要吃東西了。
insulin：胰島素
But all sorts of things can interfere with this process.
1 When you are tired
According to a 2011 study by researchers at Columbia University in the US, those who are sleep-deprived eat almost 300 calories a day more than those who get enough sleep.
根據美國哥倫比亞大學2011年研究人員的一項研究，那些睡眠不足的人每天攝入的熱量幾乎比那些睡眠充足的人多300卡路里。
This is because levels of the hormone ghrelin, which tells the brain we need to eat, increase when we don't get enough sleep.
這是因爲當我們沒有足夠的睡眠時，飢餓激素會增加，會告訴大腦需要吃更多的東西。
The Columbia researchers noted that the women who didn't get enough sleep took in more fat rising by around 30g on sleep-deprived days — four times as much as the average increase for men.
哥倫比亞大學的研究人員指出，睡眠不足的女性在睡眠不足的日子裡攝入的脂肪增加了約30克。這是男性平均增加量的四倍。
2 Troubled times
In a 2013 study, people who were primed to expect "tough times ahead" ate more food than people who listened to neutral messages.
在2013年的一項研究中，那些得知不久會遇到“艱難時期”的人會比獲得中性信息的人吃更多的食物。
primed：準備好的
It's thought that hearing about troubled times causes a survival instinct to kick in, leading to cravings for high-calorie snacks such as chocolate.
一聽說“有麻煩了”，人的生存本能就被激發了，對巧克力等高熱量零食的渴望也隨之增加。
3 'Naughty' food cravings
Tempted by that extra biscuit? Then just enjoy it — as researchers have found that when you feel guilty about a pleasurable experience, the guilt itself becomes pleasurable, so encouraging you to do it more.
還想再吃一塊小餅乾？吃就吃吧，開心一點。研究人員發現，當你對某個愉快的體驗感到內疚時，內疚本身也會帶來快感，進而鼓勵你再次去做這件事。
"If we consider something a naughty pleasure, it can psychologically drive the appetite and the guilt may make you want to eat more," says Cary Cooper, at the University of Lancaster.
蘭卡斯特大學的Cary Cooper說，如果我們認爲某件事會帶來不守規矩的快感，它會在心理上促進食慾，而這種內疚可能會讓你想要吃更多。
The appetite center of the brain also lies very close to the area governing mood — the limbic system — which is why changes in the way we feel may affect appetite.
大腦中的食慾控制區域非常接近情緒控制區域——邊緣系統——這就是爲什麼我們的情緒變化會影響食慾。
limbic：邊緣的
4 Mobiles' blue light
The bright blue light emitted by devices such as smartphones and tablets may give an unwelcome boost to your appetite.
Research this year found that your appetite continued to increase when you are exposed to the light.
今年的研究發現，藍光下你的食慾會持續增加。
It also altered people's metabolism, as blood tests showed that the blue-light subjects had higher insulin and glucose levels.
藍光的照射還會改變人們的新陳代謝。血液測試顯示，接受藍光受試者的胰島素和葡萄糖水平都更高。
metabolism /m 't b l z m/：新陳代謝
glucose /'ɡlukos/：葡萄糖
One possible explanation is that bright blue light at night confuses our body clock, which has a role in controlling when we feel the need to eat.
一種可能的解釋是，夜間明亮的藍光會干擾我們的生物鐘。而生物鐘可以控制我們什麼時候覺得需要進食。
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來源：每日郵報