The Truth About Breakfast: You Don’t Need It早餐真相：无须食之

辛西娅·格雷伯

Much has been made about the importance of a good breakfast to a healthy lifestyle. It gives you energy to start your day， according to conventional wisdom， and scientific studies conducted a decade ago had proclaimed that eating breakfast was the key to maintaining a healthy weight.

Breakfast skippers are plagued with well-meaning spouses， partners， family members， and friends， all insisting that they should eat something in the morning. But， according to nutrition scientist P. K. Newby， that advice was based on what’s known as observational studies， in which scientists follow groups of people and observe the outcomes. The result had seemed to indicate that people who lost weight or maintained a healthy weight ate breakfast. The problem， Newby told us， is that those studies didn’t isolate breakfast as the important factor. It could be， she says， that those who lost weight also exercised more， or one of dozens of other variables.

Then， in 2014， a group of researchers at the University of Alabama published a study that took a more rigorous look at this question. They enlisted 300 participants and randomly assigned them to eat breakfast， to skip breakfast， or to simply go about their normal routine. After 16 weeks， they found no difference in weight loss among the three groups.

Meanwhile， in a similarly controlled Cornell University study， people who skipped breakfast consumed fewer calories by the end of the day. And， in a smaller study at the University of Bath， people who skipped breakfast also seem to have consumed slightly fewer calories during the day， though they then expended slightly less energy.

Based on this new research， the bottom line， Newby says， is this： if you’re not hungry in the morning， there’s no harm in skipping breakfast when it comes to weight management. “It’s the what that is more important than the when， when it comes to breakfast，” she says， which also means that grabbing a sugary muffin， doughnut， or other pastry， just to eat something in the morning， is a worse idea than eating nothing at all.

Reject the cult of juice

Everybody on the Internet has embarked on a juice cleanse. But you don’t have to feel guilty for sticking to solids： without the accompanying fiber in fruit， juice delivers a straight shot of sugar.

Juice， like sugary cereals， muffins， and white bread， is “quickly metabolized，” said Newby. “These foods lead to a spike in sugar and insulin， and then it dissipates. And so then， in a short period of time， you feel hungry again.” That， she continues， can lead to overeating and weight gain. And there are long-term health consequences as well： she says diets high in refined carbohydrates are a risk factor for type 2 diabetes and cardiovascular disease.

Newby says that the most important thing to understand about breakfast is that it’s simply another meal. It may seem as though we should eat only breakfast foods—cereal， juice， bagels—at breakfast time， but， as historian Abigail Carroll explains during this episode of Gastropod， that’s just a historical hangover from nineteenth-century American health reformers. And， as Newby points out， we already know what makes a healthy meal at any time of day： put vegetables at the center of the plate， accompanied by whole grains， beans， nuts， and healthy fats.

The first cup of coffee

Though Newby says that it’s what you eat that matters， not when， that may not be the case when it comes to coffee. We spoke to neuroscience PhD candidate Steven Miller， studying at the Uniformed Services University of the Health Sciences， about chronopharmacology， or the science of how brain chemistry interacts with drugs， in order to learn how timing affects the most popular stimulant in the world： caffeine.

Cortisol， the stress hormone that helps us feel alert and energized， peaks at about 8 or 9am， at least for people who work a typical 9-to-5 job and sleep during the same hours each night. Most people， says Miller， don’t need caffeine to give them a boost at a time they’re already naturally alert. In addition， drinking a caffeinated beverage at a time when you’re already sharp could lead to desensitization， which， Miller explains， means that you’ll need an increasing amount of the drug—in this case caffeine—to get the same effect. For the best morning buzz based on brain biology， Miller recommends saving your coffee fix until 9：30am， when cortisol levels are starting to drop off.

He admits， though， that his recommendation doesn’t hold true for everyone： anyone whose sleep schedule is not regular or who works evening or night shifts will have a different cortisol production rhythm. In fact， he actually doesn’t follow his own chronopharmacological advice. Miller told Gastropod that， as a neuroscience PhD student， he works long， irregular hours and gets little sleep， and he always starts off his day， at any hour， with an extra strong caffeinated beverage.

The most capitalist meal of all

Miller’s decision to design his coffee routine around his work schedule， rather than biology， isn’t surprising given the history of breakfast. As we learn from journalist Malia Wollan， while breakfast foods may be different all around the world， it’s the first meal to change in immigrant households.

And， as Three Squares author Abigail Carroll explains， those classic American breakfast foods can be traced directly back to the Industrial Revolution and its transformation of labor—combined with some entrepreneurial innovations in processing， packaging， and marketing that were first pioneered in breakfast cereal but went on to transform the American diet.

吃好早餐對于健康生活方式的重要意义历来备受关注。传统观念认为，这会让我们有精力投入新的一天。十年前的科学研究也表明，吃早餐是保持健康体重的关键。

不吃早餐的人为此饱受困扰，好心的伴侣、家人和朋友都坚持认为他们早上应吃点儿东西。但营养学家纽比称此建议不过是来自观察性研究——当时科学家跟踪几组人，通过观察似乎得出这样的结论：减掉体重或保持健康体重的人都吃早餐。她指出问题是这些研究并没有把早餐单列为重要指标。实际上，那些瘦了的人很可能同时做更多锻炼，也可能受其他众多因素影响。

2014年，阿拉巴马大学的研究人员开展了另一项研究，对这个问题进行了更为严谨的探讨。他们召集了300名实验参与者，随机分配为吃早餐、不吃早餐及遵循日常饮食习惯3个小组。16周后，3组人在减重方面并无明显差异。

无独有偶，康奈尔大学进行了类似的对照实验，发现不吃早餐的人一天下来摄入的卡路里更少。巴斯大学的一项小规模研究也表明，不吃早餐的人似乎每天摄入的卡路里更少些，不过他们消耗的也更少。

基于上述新研究，纽比认为，关于早餐的基本论点是：早上不饿时，不吃早餐对体重管理并无坏处。她还补充道：“对早餐而言，吃什么比什么时候吃更重要。”这就是说，为了早上吃点儿什么而匆匆吞下甜松饼、甜甜圈或其他糕点比起什么都不吃更糟。

不要迷信果汁

果汁节食现在风靡网络，但吃固体食物并非十恶不赦：没有了水果中富含的纤维，果汁就是一杯糖水而已。

纽比说，果汁和甜麦片、松饼以及白面包一样，都会“很快代谢”。“这些食物会使糖分和胰岛素达到峰值，很快消耗殆尽。短时间内你又会感到饥饿。”纽比说这会导致过度进食和体重增加，还会产生长期的健康隐患：富含精致碳水化合物的饮食是导致2型糖尿病和心血管疾病的风险因素。

她还说，关键要意识到早餐只是一顿饭而已。我们似乎习惯了在早餐时间只吃某些早餐食物，如麦片、果汁、百吉饼。但是在本集《软体动物》中，历史学家阿比盖尔·卡罗尔把这解释成“19世纪美国健康改革家们的历史遗留”。正如纽比所说，我们早就知道一天中三餐的健康饮食为何：蔬菜为主，全麦制品、豆制品、坚果及适量脂肪为辅。

第一杯咖啡

尽管纽比说吃的时间不重要，重要的是吃什么，但这不适用于喝咖啡。健康科学统一服务大学的神经科学博士生史蒂文·米勒告诉了我们一些关于时辰药理学的知识。这门科学旨在通过研究大脑化学物质与药物的反应，从而揭示服用时间对世界上最受欢迎的兴奋剂——咖啡因的影响。

皮质醇是帮助我们保持清醒、精力充沛的压力荷尔蒙。它在早上八九点钟达到分泌高峰期——至少对朝九晚五、作息规律的人们如此。米勒说，大部分人在自然清醒的状态下，都不需要咖啡因提神。此外，在清醒的时候喝含有咖啡因的饮料反而会导致脱敏，米勒解释说，这意味着此后需要增加咖啡因的剂量才能达到提神的效果。基于大脑生物学，米勒认为要想早上有活力，就要九点半以后再摄入咖啡因，那时皮质醇的水平才开始下降。

然而，米勒也承认他的建议并不具备普适性。作息习惯不规律的人、上晚班或值夜班的人都会有不同的皮质醇分泌特点。其实他本人也不遵循时辰药理学的规律。米勒对《软体动物》节目组说，身为一个神经科学的博士生，他的工作时间长、不规律，睡眠时间又少。因此无论何时，他都在喝完一杯浓咖啡之后，才开始一天的工作。

最有资本主义特色的一餐

米勒决定根据自己的工作日程，而不是生物规律来安排自己的咖啡时间。这从早餐的历史来说并不出乎意料。我们从记者马利亚·沃兰处了解到，虽然世界各地早餐食物截然不同，早餐是移民家庭改变饮食习惯的开始。

正如《三个正方形：美国膳食之发明》的作者阿比盖尔·卡罗尔所说，这些经典的美国早餐食物可以直接追溯到工业革命及其对劳动力的改造上，同时一些企业家也在加工、包装和营销方面进行了革新——革新始于早餐麦片，继而改变了美国人的饮食。