辛西婭·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義歷來備受關(guān)注。傳統(tǒng)觀念認(rèn)為，這會讓我們有精力投入新的一天。十年前的科學(xué)研究也表明，吃早餐是保持健康體重的關(guān)鍵。

不吃早餐的人為此飽受困擾，好心的伴侶、家人和朋友都堅持認(rèn)為他們早上應(yīng)吃點兒東西。但營養(yǎng)學(xué)家紐比稱此建議不過是來自觀察性研究——當(dāng)時科學(xué)家跟蹤幾組人，通過觀察似乎得出這樣的結(jié)論：減掉體重或保持健康體重的人都吃早餐。她指出問題是這些研究并沒有把早餐單列為重要指標(biāo)。實際上，那些瘦了的人很可能同時做更多鍛煉，也可能受其他眾多因素影響。

2014年，阿拉巴馬大學(xué)的研究人員開展了另一項研究，對這個問題進(jìn)行了更為嚴(yán)謹(jǐn)?shù)奶接?。他們召集?00名實驗參與者，隨機分配為吃早餐、不吃早餐及遵循日常飲食習(xí)慣3個小組。16周后，3組人在減重方面并無明顯差異。

無獨有偶，康奈爾大學(xué)進(jìn)行了類似的對照實驗，發(fā)現(xiàn)不吃早餐的人一天下來攝入的卡路里更少。巴斯大學(xué)的一項小規(guī)模研究也表明，不吃早餐的人似乎每天攝入的卡路里更少些，不過他們消耗的也更少。

基于上述新研究，紐比認(rèn)為，關(guān)于早餐的基本論點是：早上不餓時，不吃早餐對體重管理并無壞處。她還補充道：“對早餐而言，吃什么比什么時候吃更重要。”這就是說，為了早上吃點兒什么而匆匆吞下甜松餅、甜甜圈或其他糕點比起什么都不吃更糟。

不要迷信果汁

果汁節(jié)食現(xiàn)在風(fēng)靡網(wǎng)絡(luò)，但吃固體食物并非十惡不赦：沒有了水果中富含的纖維，果汁就是一杯糖水而已。

紐比說，果汁和甜麥片、松餅以及白面包一樣，都會“很快代謝”?！斑@些食物會使糖分和胰島素達(dá)到峰值，很快消耗殆盡。短時間內(nèi)你又會感到饑餓?！奔~比說這會導(dǎo)致過度進(jìn)食和體重增加，還會產(chǎn)生長期的健康隱患：富含精致碳水化合物的飲食是導(dǎo)致2型糖尿病和心血管疾病的風(fēng)險因素。

她還說，關(guān)鍵要意識到早餐只是一頓飯而已。我們似乎習(xí)慣了在早餐時間只吃某些早餐食物，如麥片、果汁、百吉餅。但是在本集《軟體動物》中，歷史學(xué)家阿比蓋爾·卡羅爾把這解釋成“19世紀(jì)美國健康改革家們的歷史遺留”。正如紐比所說，我們早就知道一天中三餐的健康飲食為何：蔬菜為主，全麥制品、豆制品、堅果及適量脂肪為輔。

第一杯咖啡

盡管紐比說吃的時間不重要，重要的是吃什么，但這不適用于喝咖啡。健康科學(xué)統(tǒng)一服務(wù)大學(xué)的神經(jīng)科學(xué)博士生史蒂文·米勒告訴了我們一些關(guān)于時辰藥理學(xué)的知識。這門科學(xué)旨在通過研究大腦化學(xué)物質(zhì)與藥物的反應(yīng)，從而揭示服用時間對世界上最受歡迎的興奮劑——咖啡因的影響。

皮質(zhì)醇是幫助我們保持清醒、精力充沛的壓力荷爾蒙。它在早上八九點鐘達(dá)到分泌高峰期——至少對朝九晚五、作息規(guī)律的人們?nèi)绱恕Ｃ桌照f，大部分人在自然清醒的狀態(tài)下，都不需要咖啡因提神。此外，在清醒的時候喝含有咖啡因的飲料反而會導(dǎo)致脫敏，米勒解釋說，這意味著此后需要增加咖啡因的劑量才能達(dá)到提神的效果?；诖竽X生物學(xué)，米勒認(rèn)為要想早上有活力，就要九點半以后再攝入咖啡因，那時皮質(zhì)醇的水平才開始下降。

然而，米勒也承認(rèn)他的建議并不具備普適性。作息習(xí)慣不規(guī)律的人、上晚班或值夜班的人都會有不同的皮質(zhì)醇分泌特點。其實他本人也不遵循時辰藥理學(xué)的規(guī)律。米勒對《軟體動物》節(jié)目組說，身為一個神經(jīng)科學(xué)的博士生，他的工作時間長、不規(guī)律，睡眠時間又少。因此無論何時，他都在喝完一杯濃咖啡之后，才開始一天的工作。

最有資本主義特色的一餐

米勒決定根據(jù)自己的工作日程，而不是生物規(guī)律來安排自己的咖啡時間。這從早餐的歷史來說并不出乎意料。我們從記者馬利亞·沃蘭處了解到，雖然世界各地早餐食物截然不同，早餐是移民家庭改變飲食習(xí)慣的開始。

正如《三個正方形：美國膳食之發(fā)明》的作者阿比蓋爾·卡羅爾所說，這些經(jīng)典的美國早餐食物可以直接追溯到工業(yè)革命及其對勞動力的改造上，同時一些企業(yè)家也在加工、包裝和營銷方面進(jìn)行了革新——革新始于早餐麥片，繼而改變了美國人的飲食。