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早餐真是一天当中最重要的一餐吗?

更新时间:2019/3/10 10:42:18 来源:纽约时报中文网 作者:佚名

Is breakfast really the most important meal of the day?
早餐真是一天当中最重要的一餐吗?

Along with old classics like ‘carrots give you night vision’ and ‘Santa doesn’t bring toys to misbehaving children’, one of the most well-worn phrases in the arsenal of tired parents everywhere is that breakfast is the most important meal of the day. Many of us grow up believing that skipping breakfast is a dietary travesty – even if only two thirds of adults in the UK eat breakfast regularly, according to the Association of UK Dieticians (BDA), and around three-quarters of Americans.

除了“吃胡萝卜能增进夜间视力”和“不乖的话圣诞老人不会送玩具”这样的老话之外,天下疲惫不堪的父母说得最多的一句话,就是早餐是一天当中最重要的一餐了。我们许多人在成长过程中都相信,不吃早餐会破坏饮食规律,尽管只有三分之二的英国人(英国营养协会BDA的数据),以及四分之三左右的美国人会经常吃早餐。

The clue for why breakfast is supposed to be important is in its name: we’re advised to eat it to break our overnight fast.

为什么早餐如此重要,线索就在它的英文名字“breakfast”里:我们得到的线索是,早餐是结束(break)禁食(fast)后的第一次进食。

“The body uses a lot of energy stores for growth and repair through the night,” explains dietician Sarah Elder. “Eating a balanced breakfast helps to up our energy, as well as protein and calcium used throughout the night.”

营养学家埃尔德(Sarah Elder)解释说,“在夜间,身体动用了大量的能量储备进行生长和修复,吃上一顿营养均衡的早餐,有助于补上我们夜间所消耗的能量,以及蛋白质和钙。”

But there’s widespread disagreement over whether breakfast should keep its top spot in the hierarchy of meals. As well as the rising popularity of fasting diets, there have been concerns around the sugar content of cereal and the food industry’s involvement in pro-breakfast research – and even one claim from an academic that breakfast is “dangerous”.

不过,对于早餐是否应该在一日三餐中高居头把交椅,是存在相当分歧的。除了间歇性禁食的日益流行,人们也一直担心谷物中的糖分含量,以及食品行业参与的支持早餐的研究,甚至有学者声称,早餐是“危险的”。

So what’s the reality? Is breakfast a necessary start to the day… or a marketing ploy by cereal companies?

实际情况究竟是怎样的呢?早餐究竟是一天必不可少的开始,还是谷物公司的营销策略?

Weighty decision

重要决定

The most researched aspect of breakfast (and breakfast-skipping) has been its links to obesity. Scientists have different theories as to why there’s a relationship between the two.

吃早餐和不吃早餐这件事,研究最多的是它与肥胖的关系。对于两者之间的关联,科学家们持有不同的理论。

In one US study that analysed the health data of 50,000 people over seven years, researchers found that those who made breakfast the largest meal of the day were more likely to have a lower body mass index (BMI) than those who ate a large lunch or dinner. The researchers argued that breakfast helps increase satiety, reduce daily calorie intake, improve the quality of our diet – since breakfast foods are often higher in fibre and nutrients – and improve insulin sensitivity at subsequent meals, which can be a risk for diabetes.

美国有一项研究,对5万人长达7年的健康数据进行了分析,结果研究人员发现,那些重视早餐丰盛程度的人,比在中午或者晚上大吃一顿的人更有可能拥有较低的身高体重指数(BMI)。研究人员认为,早餐有助于增加饱腹感,减少每日卡路里的摄入量,改善我们的饮食质量,因为早餐吃的东西往往含有更高的纤维含量和营养成分,并增加对随后餐食的胰岛素敏感性,较低的胰岛素敏感性存在患糖尿病风险。

But as with any study of this kind, it was unclear if that was the cause – or if breakfast-skippers were just more likely to be overweight to begin with.

但就像任何此类研究一样,尚不清楚这究竟是原因,或者是不吃早餐的人从一开始体重超重的可能性就要大一些。

To find out, researchers designed a study in which 52 obese women took part in a 12-week weight loss programme. All had the same number of calories over the day, but half had breakfast, while the other half did not.

为了找到答案,科学家设计了一项研究,让52名肥胖女性参与一个为期12周的减肥计划。所有人每天摄入相同数量的卡路里,但一半人吃早餐,一半人不吃。

What they found was that it wasn’t breakfast itself that caused the participants to lose weight: it was changing their normal routine. The women who said before the study that they usually ate breakfast lost 8.9kg when they stopped having breakfast, compared to 6.2kg in the breakfast group. Meanwhile, those who usually skipped breakfast lost 7.7kg when they started eating it – and 6kg when they continued to skip it.

结果发现,并不是早餐本身导致参与者减肥:而是日常饮食规律的改变。那些声称在研究之前就有吃早餐习惯的人在试验期间不吃早餐后减重8.9公斤,而吃早餐组是6.2公斤。与此同时,那些经常不吃早餐的人当中,在试验期间开始吃早餐后减重7.7公斤,而继续不吃早餐的人是6公斤。

If breakfast alone isn’t a guarantee of weight loss, why is there a link between obesity and skipping breakfast?

如果仅仅吃早餐并不能保证减肥,那为什么肥胖和不吃早餐之间确实有联系的呢?

Alexandra Johnstone, professor of appetite research at the University of Aberdeen, argues that it may simply be because breakfast-skippers have been found to be less knowledgeable about nutrition and health.

阿伯丁大学(University of Aberdeen)研究食欲的教授约翰斯通(Alexandra Johnstone)认为,这可能只是因为不吃早餐的人,对营养和健康的知识了解比较少。

“There are a lot of studies on the relationship between breakfast eating and possible health outcomes, but this may be because those who eat breakfast choose to habitually have health-enhancing behaviours such as not smoking and regular exercise,” she says.

她说:“对于吃早餐与可能的健康结果之间的关联,有很多研究,但这可能是因为那些吃早餐的人通常会选择有益健康的习惯和行为,像是不抽烟、经常做运动。”

A 2016 review of 10 studies looking into the relationship between breakfast and weight management concluded there is “limited evidence” supporting or refuting the argument that breakfast influences weight or food intake, and more evidence is required before breakfast recommendations can be used to help prevent obesity.

2016年,对10项研究早餐与体重管理之间关系的分析得出这样的结论:无论是支持还是反对早餐影响体重或者食物摄入量的论点都“证据有限”,而且在推荐早餐可能有助于预防肥胖之前,还需要更多的证据。

Feast or fast?

吃还是不吃?

Intermittent fasting, which involves fasting overnight and into the next day, is gaining ground among those looking to lose or maintain their weight or improve their health.

在那些希望减肥、保持体重或者改善健康状况的人当中,间歇性禁食,包括通宵禁食到第二天正在变得越来越流行。

One pilot study published in 2018, for example, found that intermittent fasting improves blood sugar control and insulin sensitivity and lowers blood pressure. Eight men with pre-diabetes were assigned one of two eating schedules: either eating all their calories between 9:00 and 15:00, or eating the same number of calories over 12 hours. The results for the 9:00-15:00 group were found to be on par with medicine that lowers blood pressure, according to Courtney Peterson, the study’s author and assistant professor of nutrition sciences at the University of Alabama at Birmingham.

例如,2018年发表的一份试点研究发现,间歇性禁食可以改善血糖控制和胰岛素敏感性,并降低血压。8名前期糖尿病患者被安排了两种饮食计划:一种在9点到15点之间摄入全部卡路里,另一种在12个小时内摄入相同数量的卡路里。该研究的作者、亚拉巴马大学伯明翰分校(University of Alabama at Birmingham)营养科学助理教授彼得森(Courtney Peterson)说,研究结果发现,9点到15点那一组的结果与降压药不相上下。

Still, the study’s small size means more research is needed on its possible long-term benefits.

尽管如此,由于这项研究规模小,意味着对间歇性禁食可能的长期收益还需要进行更多研究。

If skipping breakfast (and other food outside of a restricted time slot) could potentially be good for you, does that mean breakfast could be bad for you? One academic has said so, arguing that breakfast is ‘dangerous’: eating early in the day causes our cortisol to peak more than it does later on. This causes the body to become resistant to insulin over time and can lead to type 2 diabetes.

如果不吃早餐(以及限制时段之外的其他食物)对你可能有好处的话,那么这是否意味着吃早餐对人有害呢?有学者曾经说过这样的话,认为吃早饭“有害”:吃得早比吃得晚令我们的皮质醇分泌更多。长此以往,会导致身体产生胰岛素抵抗,患上II型糖尿病。

But Fredrik Karpe, professor of metabolic medicine at Oxford Centre for Diabetes, Endocrinology and Metabolism, argues this isn’t the case. Instead, higher levels of cortisol in the morning are just part of our body’s natural rhythm.

但牛津大学糖尿病、内分泌及代谢病中心(Oxford Centre for Diabetes, Endocrinology and Metabolism)的代谢医学教授卡普(Fredrik Karpe)就认为,情况并非如此。相反,皮质醇水平在早上升高只是我们身体自然节奏的一部分。

Not only that, but breakfast is key to jumpstarting our metabolism, he says. “In order for other tissues to respond well to food intake, you need an initial trigger involving carbs responding to insulin. Breakfast is critical for this to happen,” Karpe says.

他说,不仅如此,早餐也是促进新陈代谢的关键。“为了让身体其他组织对食物摄入做出良好反应,你需要一个对胰岛素做出反应的碳水化合物初始触发装置。早餐是触发的关键之所在,”卡普说。

A randomised control trial published last year involving 18 people with, and 18 people without, diabetes found that skipping breakfast disrupted the circadian rhythms of both groups and led to larger spikes in blood glucose levels after eating. Eating breakfast, the researchers conclude, is essential for keeping our body clock running on time.

去年发表的一项随机对照试验涉及18名糖尿病患者和18名健康的人,结果发现,不吃早餐会扰乱两组人的生理节奏,导致进食后的血糖水平出现更大峰值。研究者得出的结论是,吃早餐对于维持我们的生物钟正常运转至关重要。

Peterson says those who skip breakfast can be divided into those who either skip breakfast and eat dinner at a normal time – getting the benefits of intermittent fasting, if not breakfast – or those who skip breakfast and eat dinner late.

彼得森说,不吃早餐的人可以分为两种,一种是不吃早餐,但晚餐时间正常的人(如果不吃早餐的话,可以获得间歇性禁食的好处);另一种是不吃早餐,晚餐也吃得晚的人。

“For those who eat dinner later, their risk of obesity, diabetes and cardiovascular disease goes through the roof. While it seems breakfast is the most important meal of the day, it might actually be dinner,” she says.

她说,“对于那些晚餐也吃得晚的人来说,他们患肥胖症、糖尿病和心血管疾病的风险大大增加。虽然早餐似乎是一天中最重要的一餐,但实际上晚餐可能才是最重要的一顿。”

“Our blood sugar control is best early in the day. When we eat dinner late, that’s when we’re most vulnerable because our blood sugar is worst. There’s more research to do, but I’m confident you shouldn’t skip breakfast and have dinner late.”

“我们的血糖控制在早上的时候是最好的。晚餐吃得晚,那是我们最容易受到伤害的时候,因为那会儿我们的血糖状况最差。虽然还需要做很多的研究,但我想当确定,你不应该不吃早餐,然后晚餐还吃得晚。”

She says we should think of our circadian rhythm as an orchestra.

她说,我们应该把自己的生理节奏想像成一支管弦乐队。

“There are two parts of our circadian clock. There’s the master clock in the brain, which we should think of as analogous to a conductor of an orchestra, and the other half is in every organ, which has a separate clock,” she says.

“我们的生物钟分为两个部分。大脑里有一个主时钟,我们应该把它想成管弦乐队的指挥,而另一半在每个器官里,每个器官都有一个单独的时钟,”她说。

And that ‘orchestra’ is set by two outside factors: bright light exposure and our eating schedule.

这支“管弦乐队”是由两个外部因素决定的:明亮的日光和我们的饮食时间安排。

“If you’re eating when you’re not getting bright light exposure, the clocks that control metabolism are in different time zones, creating conflicting signals as to whether to rev up or down.”

“如果你在不见天光的情况下吃东西,控制新陈代谢的时钟就会位于不同的时区里,在究竟是加快速度还是放慢速度方面产生相互矛盾的信号。”

It’s like two halves of an orchestra playing different songs, Peterson explains, and this is why eating late impairs blood sugar and blood pressure levels.

彼得森解释说,这就像管弦乐队分成两半,各自演奏不同的歌曲,这就是为什么吃得晚会损害血糖和血压水平的原因。

Researchers from the University of Surrey and University of Aberdeen are halfway through research looking into the mechanisms behind how the time we eat influences body weight. Early findings suggest that a bigger breakfast is beneficial to weight control.

来自英国萨里大学(University of Surrey)和阿伯丁大学的研究人员正在研究进食时间如何影响体重的原理。早期的研究表明,丰盛的早餐有助于控制体重。

Health food

健康食品

Breakfast has been found to affect more than just weight. Skipping breakfast has been associated with a 27% increased risk of heart disease, a 21% higher risk of type 2 diabetes in men, and a 20% higher risk of type 2 diabetes in women.

研究还发现,早餐影响的不仅仅是体重。不吃早餐会使患上心脏病的风险增加27%,男性患II型糖尿病的风险增加21%,女性患II型糖尿病的风险增加20%。

One reason may be breakfast’s nutritional value – partly because cereal is fortified with vitamins. In one study on the breakfast habits of 1,600 young people in the UK, researchers found that the fibre and micronutrient intake, including of folate, vitamin C iron and calcium, was better in those who had breakfast regularly. There have been similar findings in Australia, Brazil, Canada and the US.

一个原因可能是因为早餐营养价值高,部分因为早餐谷物片添加了维生素。英国一项研究,调查了1600名年轻人的早餐习惯后发现,经常吃早餐的人能摄入更多的纤维和微量元素,包括叶酸、维生素C、铁和钙在内。澳大利亚、巴西、加拿大和美国也有类似的发现。

Breakfast is also associated with improved brain function, including concentration and language. A review of 54 studies found that eating breakfast can improve memory, though the effects on other brain functions were inconclusive. However, one of the review’s researchers, Mary Beth Spitznagel, says there is “reasonable” evidence breakfast does improve concentration – there just needs to be more research.

早餐还能改进大脑功能,包括提高注意力和语言能力。一篇对54项研究的文献综合分析发现,吃早餐可以改善记忆,但对大脑其他功能的影响尚无定论。然而,该论文的作者之一施皮茨纳格尔(Mary Beth Spitznagel)表示,有“合理的”证据表明,早餐的确可以提高注意力,只是还需要更多的研究。

“Looking at studies that tested concentration, the number of studies showing a benefit was exactly the same as the number that found no benefit,” she says.

她说:“看看那些测试注意力的研究,结论是有益的研究的数量和发现无益的研究的数量是完全相同的。”

“And no studies found that eating breakfast was bad for concentration.”

“但没有研究发现,吃早餐不利于注意力的集中。”

What’s most important, some argue, is what we eat for breakfast.

一些人认为,最重要的是,我们早餐吃的什么。

High-protein breakfasts have been found particularly effective in reducing food cravings and consumption later in the day, according to research by the Australian Commonwealth Scientific and Industrial Research Organisation.

澳大利亚的联邦科学与工业研究组织(Commonwealth Scientific and Industrial Research Organisation)的研究发现,蛋白质含量丰富的早餐,对于降低当天随后时间的食欲及减少食物摄取量,特别有效。

While cereal remains a firm favourite among breakfast consumers in the UK and US, a recent Which? investigation into the sugar content of ‘adult’ breakfast cereals found that some cereals contain more than three quarters of the recommended daily amount of free sugars in each portion, and sugar was the second or third highest ingredient in seven out of 10 flaked cereals.

虽然麦片玉米片这类早餐谷物是英国和美国的早饭首选,但最近英国消费者权益组织《Which?》对成人早餐麦片含糖量的调查发现,一些早餐谷物片中,每份所含游离糖达到每日推荐摄入量的四分之三,在片状谷物中,糖分在成分列表中位居第二位或者第三位的,占到了十分之七。

But some research suggests if we’re going to eat sugary foods, it’s best to do it early. One study found that changing levels of the appetite hormone leptin in the body throughout the day coincide with having our lowest threshold for sweet food in a morning, while scientists from Tel Aviv University have found that hunger is best regulated in the morning. They recruited 200 obese adults to take part in a 16-week-long diet, where half added dessert to their breakfast, and half didn’t. Those who added dessert lost an average of 40lbs (18kg) more – however, the study was unable to show the long-term effects.

但一些研究表明,如果我们要吃甜食,最好早点吃。一项研究发现,人体内的食欲荷尔蒙瘦素的水平在一天当中是处在不断变化中的,早间摄入甜食的门槛最低。特拉维夫大学(Tel Aviv University)的科学家发现,饥饿感在早上控制得最好。他们招募了200名肥胖的成年人参加了为期16周的节食,一半人的早餐中加了甜点,另一半则没有。那些加入了甜点的,平均减掉了40磅(18公斤),不过,这项研究无法证实其长期效果。

A review of 54 studies found that there is no consensus yet on what type of breakfast is healthier, and conclude that the type of breakfast doesn’t matter as much as simply eating something.

一篇对54项研究的文献综合分析发现,对于哪种类型的早餐更健康,人们还没有达成共识,并且该论文认为,早餐的类型,远不如吃早餐这件事本身来得重要。

Final take

最后一点

While there’s no conclusive evidence on exactly what we should be eating and when, the consensus is that we should listen to our own bodies and eat when we’re hungry.

虽然没有确切的证据表明我们应该吃什么和什么时候吃,但共识是,想吃什么就吃什么,饿了就吃。

“Breakfast is most important for people who are hungry when they wake up,” Johnstone says.

约翰斯通说:“对于那些醒来时肚子饿的人来说,早餐最重要。”

For instance, research shows that those with pre-diabetes and diabetes may find they have better concentration after a lower-GI breakfast such as porridge, which is broken down more slowly and causes a more gradual rise in blood sugar levels.

例如,研究表明,那些患有糖尿病前期和糖尿病的人可能会发现,在享用了一顿低升糖指数的早餐(比如西式的谷物粥)后,注意力会更集中,低升糖指数的早餐分解较慢,血糖水平上升也较趋平稳。

Every body starts the day differently – and those individual differences, particularly in glucose function, need to be researched more closely, Spitznagel says.

施皮茨纳格尔说,每个人的身体是以不同的方式开始自己的一天,对于这些个体的差异,尤其是葡萄糖功能方面的差异,还需要更深入地研究。

In the end, the key may be to be mindful of not over-emphasising any single meal, but rather looking at how we eat all day long.

最后,关键还恐怕是要注意,不可过分强调三餐中任何一餐的重要性,而是要看看我们整天都是怎么在吃。

“A balanced breakfast is really helpful, but getting regular meals throughout the day is more important to leave blood sugar stable through day, that helps control weight and hunger levels,” says Elder.

埃尔德说:“均衡的早餐真的很有帮助,但一整天的规律饮食,对保持全天血糖稳定更重要,而且有助于控制体重和饥饿水平。”

“Breakfast isn’t the only meal we should be getting right.”

“早餐不是我们唯一要吃对的一餐。”

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