BBC：為啥子精神壓力會讓你變胖？
【世界決定視界】【視界決定世界】
歡迎打開「我與我們的世界」，從此，讓我們一起「縱覽世界之風雲變幻、洞察社會之脈搏律動、感受個體之生活命運、挖掘自然之點滴奧妙」。
我與我們的世界，既是一個「奮鬥」的世界，也是一個「思考」的世界。奮而不思則罔，思而不奮則殆。這個世界，你大，它就大；你小，它就小。
歡迎通過上方公眾號名稱打開公眾號「查看歷史消息」來挖掘往期文章，因為，每期都能讓你「走近」不一樣的世界、帶給你不一樣的精彩。
本期導讀：肥胖（Obesity）是指體脂肪累積過多而對健康造成負面影響的身體狀態，可能導致壽命減短及各種健康問題。肥胖的標準常使用身體質量指數（BMI）來衡量，即以體重（公斤）除以身高（米）的平方。西方人認為BMI大於30 kg/m2 即為肥胖，介於25到30kg/m2間則為過重；一些東亞國家和地區採用更嚴格的標準，例如台灣行政院衛生署（現衛生福利部）於2002年4月公布台灣成人的BMI≧27 即為肥胖，24≦BMI＜27 則為過重。但幼兒並不適合用成人的BMI標準來評量。
肥胖會增加心血管疾病、第二型糖尿病、睡眠呼吸中止症、某些癌症、退化性關節炎及其他疾病的發生機會。而造成肥胖的主因常包括熱量攝取過多、欠缺運動及體質問題等，其他如基因缺陷、內分泌異常、藥物影響及精神疾病也可能造成肥胖。有種說法認為「肥胖的人由於代謝慢，因此即使吃得不多也會越來越胖」，但目前的科學證據傾向不支持此種論點，因為肥胖的人必須花更多能量維持較重的體重，所以他們的代謝率反而高於常人。
肥胖的主要治療方式有飲食計劃和運動。患者在日常飲食中必須避免高熱量（高油高糖）食物並增加高纖食物，若良好的飲食控制無法有效減重，則可以考慮搭配抗肥胖藥物來減低食慾和抑制脂肪吸收。如果飲食、運動、甚至搭配藥物都不見效，用來減少胃容積的胃內水球置放術可能會有幫助，以手術來減少胃容積或腸道長度也能直接降低食量並減少營養素的吸收。
肥胖也是一種很常見的可預防死因，是21世紀最重要的公共衛生問題之一。目前全球範圍內，成人與兒童的肥胖盛行率都在上升，且女性較男性更常發生。2014年，全球有6億名成人（13%）和4200萬名五歲以下的孩童有肥胖問題。2013年，美國醫學會將肥胖定義為一種疾病。
Why stress makes you fat
為啥子壓力會讓你變胖？
We all know what makes us fat: eating morein calories than we burn off in energy. But though this is true, it doesn"t answer the more interesting question - why do we overeat in the first place?
Why do I sometimes feel compelled to eat that bit of cake or bar of chocolate although I know I am going to regret it a few minutes later?
Is it just greed - or is something else going on?
Although self-control is important, there is mounting evidence thatstress plays a significant part in weight gain.
Chronic stress disrupts our sleep and our blood sugar levels. This leads to increased hunger and comfort eating.
And that then leads to further disrupted sleep, even higher levels of stress and even more disrupted blood sugars. In time, this can lead not only to unhealthy levels of body fat, but also to type-2 diabetes.
To see what can happen, Dr Giles Yeo, a member of the Trust Me, I"m a Doctor team, decided, with the help of scientists from Leeds University, to put himself through a particularly stressful day.
The Leeds scientists started by asking Giles to do something called theMaastricht Stress Test.
They put him in front of a computer and made him rapidly subtract a number, 17, from another number, 2,043. He kept making mistakes, which for someone like Giles is particularly stressful.
Then they got him to put his hand in a bath of ice-cold water and hold it there. Before and after these tests, the Leeds team measured Giles"s blood sugar levels.
Our blood sugar levels rise when we eat and, in a healthy person like Giles, they quickly return to normal.
But what the Leeds team found was that on the day when Giles was being deliberately stressed, his blood sugar levels took three hours to return to normal - some six times longer than on a previous, stress-free day.
The reason this happens is thatwhen you are stressed, your body goes into "fight or flight" mode.
Your body thinks it is under attack and releases glucose into your blood to provide energy for your muscles.
But if you don"t need that energy to run away from danger, then your pancreas will pump out insulin to bring those blood sugar levels back down again.
These rising levels of insulin and falling blood sugars will make you hungry - which is why you crave sugary carbs when you are stressed.
The same sort of thing happens when you have a bad night"s sleep.
A recent study carried out by researchers at King"s College, London found that if you sleep-deprived people they would consume, on average, an extra 385kcal per day, which is equivalent to the calories in a large muffin.
Children also get the munchies when they haven"t had enough sleep.
In another recent study, researchers took a small group of three- and four-year-olds (all regular afternoon nappers) and not only deprived them of their afternoon nap, but also kept them up for about two hours past their normal bedtime
The following day, the children ate 20% more calories than usual, particularly more sugar and carbohydrates. They were then allowed to sleep as much as they wanted.
The day after that, they still consumed 14% more calories than normal.
Sohow can you reduce daily stress?
One of the first things I would strongly recommend is to tryto get a good night"s sleep. This is easier said than done, but NHS Choices provides some useful tips.
You could also try some well established "stress-busting" techniques - such as exercising, gardening, mindfulness or yoga.
When I recently tested them, with the help of Prof Angela Clow, a stress expert from the University of Westminster, the mindfulness came out on top.
But a key finding of our study wasyou really only got benefit if you enjoyed it.
So do try different things and see which works best for you.
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