2018.8.3纽约时报：吃什么很重要，什么时候吃也一样

When We Eat, or Don’t Eat, May Be Critical for Health

吃什么很重要，什么时候吃也一样

Nutrition scientists have long debated the best diet for optimal health. But now some experts believe that it’s not just what we eat that’s critical for good health, but when we eat it.

长期以来，营养学家们一直在争论对于理想的健康状况而言，最佳的日常饮食是什么。但是如今一些专家认为，重要的不仅仅是吃什么，还有什么时候吃。

A growing body of research suggests that our bodies function optimally when we align our eating patterns with our circadian rhythms, the innate 24-hour cycles that tell our bodies when to wake up, when to eat and when to fall asleep. Studies show that chronically disrupting this rhythm — by eating late meals or nibbling on midnight snacks, for example — could be a recipe for weight gain and metabolic trouble.

越来越多的研究表明，当饮食模式与生物钟相匹配时，我们的身体能够以最佳状态运转。长期打乱这种规律，例如吃得很晚或是在深夜吃一点零食，都可能导致体重增加以及新陈代谢问题。

That is the premise of a new book, “The Circadian Code,” by Satchin Panda, a professor at the Salk Institute and an expert on circadian rhythms research. Dr. Panda argues that people improve their metabolic health when they eat their meals in a daily 8- to 10-hour window, taking their first bite of food in the morning and their last bite early in the evening.

以这样的结论为前提，索尔克研究所教授及人体昼夜节律研究方面专家的萨钦·潘达(Satchin Panda)在新书《节律密码》(The Circadian Code)中提出，把每天的可进食时段控制在8-10个小时之内，即在早晨吃第一顿、傍晚吃最后一顿时，有助于提升人们的新陈代谢健康。

This approach, known as early time-restricted feeding, stems from the idea that human metabolism follows a daily rhythm, with our hormones, enzymes and digestive systems primed for food intake in the morning and afternoon. Many people, however, snack and graze from roughly the time they wake up until shortly before they go to bed. Dr. Panda has found in his research that the average person eats over a 15-hour or longer period each day, starting with something like milk and coffee shortly after rising and ending with a glass of wine, a late night meal or a handful of chips, nuts or some other snack shortly before bed.

这一方法也被称为“提早限时进食法”，它源于人类的新陈代谢遵循日常节律，即我们体内的激素水平、酶以及消化系统都更倾向于在早晨和下午进食这一理念。然而很多人大约从早晨醒来一直到睡前都在吃东西。潘达博士在他的研究中发现，平均人们每天在长达15个小时或更长的时段内进食，通常是早晨起来喝一杯牛奶或咖啡，睡前再喝一杯酒、吃顿夜宵，或是一大把薯片、坚果等其他零食。

That pattern of eating, he says, conflicts with our biological rhythms.

潘达教授说，这种饮食模式与我们的生物节律相违背。

Scientists have long known that the human body has a master clock in the brain, located in the hypothalamus, that governs our sleep-wake cycles in response to bright light exposure. A couple of decades ago, researchers discovered that there is not just one clock in the body but a collection of them. Every organ has an internal clock that governs its daily cycle of activity.

科学家们早就发现人类大脑中存在一个主生物钟，它位于下丘脑，能够对亮光进行反馈，从而控制睡眠和清醒的周期。几十年前，研究者们发现人体内存在大量的生物钟，而不是仅有一个。每个器官都有一个内在的生物钟，掌管着它的日常活动周期。

During the day, the pancreas increases its production of the hormone insulin, which controls blood sugar levels, and then slows it down at night. The gut has a clock that regulates the daily ebb and flow of enzymes, the absorption of nutrients and the removal of waste. The communities of trillions of bacteria that comprise the microbiomes in our guts operate on a daily rhythm as well. These daily rhythms are so ingrained that they are programmed in our DNA: Studies show that in every organ, thousands of genes switch on and switch off at roughly the same time every day.

白天，胰腺会增加胰岛素的分泌，用以控制血糖水平，而到了晚上这一过程就会减慢。肠道也有一个生物钟，用以管理每天酶的分泌量的起伏、营养的吸收以及废物的排出。我们肠道内数以亿计的细菌构成的菌群也以日节律运转。这些日节律是如此根深蒂固，以至于它们被写入了我们的基因：研究表明，在每个器官当中，成千上万的基因都在每天大约同一时刻工作和休息。

“We’ve inhabited this planet for thousands of years, and while many things have changed, there has always been one constant: Every single day the sun rises and at night it falls,” Dr. Panda said. “We’re designed to have 24-hour rhythms in our physiology and metabolism. These rhythms exist because, just like our brains need to go to sleep each night to repair, reset and rejuvenate, every organ needs to have down time to repair and reset as well.”

“我们在这个星球上居住了数千年，尽管很多事情发生了变化，但是仍有一件事是永恒的，那就是每天太阳都会照常升起和落下，”潘达教授说。“我们在生理和代谢上被设定好拥有以24小时为周期的节律。这些节律之所以存在，是因为就像我们的大脑每晚需要修复、重启和恢复活力一样，每个器官也需要有休息时间来修复和重启。

Most of the evidence in humans suggests that consuming the bulk of your food earlier in the day is better for your health, said Dr. Courtney Peterson, an assistant professor in the department of nutrition sciences at the University of Alabama at Birmingham. Dozens of studies demonstrate that blood sugar control is best in the morning and at its worst in the evening. We burn more calories and digest food more efficiently in the morning as well.

人体内的大多数迹象都表明，白天尽早进食对我们的健康有好处，阿拉巴马大学伯明翰分校营养科学系的副教授考特尼·彼得森(Courtney Peterson)说。大量研究显示，血糖控制在早晨最佳，而在晚上最差。同时，我们在早晨燃烧卡路里及消化食物的效率也更高。

At night, the lack of sunlight prompts the brain to release melatonin, which prepares us for sleep. Eating late in the evening sends a conflicting signal to the clocks in the rest of the body that it’s still daytime, said Dr. Peterson.

晚上，光照的缺乏会促使大脑分泌褪黑素，帮助我们入睡。晚上吃得太晚会给体内其他器官发出一条与其生物钟相违背的指令，彼得森博士说。

“If you’re constantly eating at a time of day when you’re not getting bright light exposure, then the different clock systems become out of sync,” she said. “It’s like one clock is in the time zone of Japan and the other is in the U.S. It gives your metabolism conflicting signals about whether to rev up or rev down.”

“如果你持续在一天之中没有光照的时间段内饮食，那么你的体内不同的生物钟就会发生紊乱，”她说。“这就好像一个时钟在日本所在的时区，而其他的在美国。这会给你的新陈代谢发出互相矛盾的指令，到底什么时候加速运转，什么时候减速休息。”

Most people know what happens when we disrupt the central clock in our brains by flying across multiple time zones or burning the midnight oil: Fatigue, jet lag and brain fog set in. Eating at the wrong time of day places similar strain on the organs involved in digestion, forcing them to work when they are programmed to be dormant, which can increase the risk of disease, said Paolo Sassone-Corsi, the director of the Center for Epigenetics and Metabolism at the University of California, Irvine.

当我们坐飞机穿过多个时区，或是开夜车以致打乱大脑内的中央生物钟时，我们会感到疲惫，时差和大脑混沌纷至沓来。在一天中不当的时间吃东西会给涉及到消化的器官带来类似的压力，迫使他们在本该休息的时间继续工作，而这可能会增加疾病的风险，加州大学欧文分校表冠遗传学及代谢中心的主任保罗·萨森-科西(Paolo Sassone-Corsi)说。

“It’s well known that by changing or disrupting our normal daily cycles, you increase your risk of many pathologies,” said Dr. Sassone-Corsi, who recently published a paper on the interplay between nutrition, metabolism and circadian rhythms.

“众所周知，改变或打乱一个人正常生活的节律会增加患上多种疾病的风险，”萨森-科西博士(Dr. Sassone-Corsi)说。她最近发表了一篇有关营养、新陈代谢与生物节律之间相互影响的论文。

A classic example of this is shift workers, who account for about 20 percent of the country’s work force. Many frequently work overnight shifts, forcing them to eat and sleep at odd times.  Nighttime shift work is linked to obesity, diabetes, some cancers and heart disease. While socioeconomic factors are likely to play a role, studies suggest that circadian disruption can directly lead to poor health.

一个典型的例子就是轮班工作的人，他们约占国家劳动力中的20%。很多人频繁地在夜间上夜，这使得他们只能在奇怪的时间点吃饭和睡觉。夜间轮班的工作和肥胖、糖尿病、某些癌症及心脏病相关。尽管社会经济方面的因素很可能在其中起作用，但研究表明昼夜颠倒会直接导致健康恶化。

In one experiment, scientists found that assigning healthy adults to delay their bedtimes and wake up later than normal for 10 days — throwing their circadian rhythms and their eating patterns out of sync — raised their blood pressure and impaired their insulin and blood sugar control. Another study found that forcing people to stay up late just a few nights in a row resulted in quick weight gain and reduced insulin sensitivity, changes linked to diabetes.

在一项实验中，健康的成年人被要求连续10天推迟入睡时间并起得比平时更晚（这打破了他们的生物节律及饮食模式），科学家们发现，这导致他们血压升高，胰岛素及血糖控制能力下降。另一项研究发现，仅仅强迫人们连续熬几天夜也会导致体重迅速增加以及胰岛素敏感度降低，这些都是导向糖尿病的身体变化。

In 2012, Dr. Panda and his colleagues at the Salk Institute took genetically identical mice and split them into two groups. One had round-the-clock access to high-fat, high-sugar foods. The other ate the same foods but in an eight-hour daily window. Despite both groups consuming the same amount of calories, the mice that ate whenever they wanted got fat and sick while the mice on the time-restricted regimen did not: They were protected from obesity, fatty liver and metabolic disease.

2012年，潘达博士和他在索尔克研究所的同事将基因上完全相同的老鼠分成两组。一组可以随时吃到高脂肪、高糖分的食物，另一组只能在8小时的时间段内吃到相同的食物。尽管两组老鼠摄入的卡路里总数相同，但是随时都可以吃到东西的那组老鼠变胖、生病，而在规定时间内进食的老鼠却没有。

Inspired by this research, Dr. Peterson conducted a tightly controlled experiment in a small group of prediabetic men. In one phase of the study, the subjects ate their meals in a 12-hour daily window for five weeks. In the other phase, they were fed the same meals in a six-hour window beginning each morning. The researchers had the subjects eat enough food to maintain their weight so they could assess whether the time-restricted regimen had any health benefits unrelated to weight loss.

受到这一研究的启发，彼得森博士在一小群前驱糖尿病男性患者中间进行了一个严格控制变量的实验。在研究的一个阶段里，受试者连续五周在每天12小时的时段内进食。在另一阶段里，他们在从每天早晨开始的6小时内进食，吃的东西都一样。研究者们让受试者们吃足够多的东西以保持他们的体重不变，这样研究者就能评估严格控制时间的饮食方式是否能带来与减重无关的健康益处。

It did. On the time-restricted regimen, the men had lower insulin, reduced levels of oxidative stress, less nighttime hunger and significantly lower blood pressure. Their systolic pressure, the top number, fell by roughly 11 points, and their diastolic pressure dropped by 10 points.

确实如此。在严格控制进食时间的阶段内，受试者们显现出更低的胰岛素水平、更低的氧化应激程度、更少的夜间饥饿以及大大降低的血压值。他们的收缩压下降了大约11个点，舒张压下降了大约10个点。

“It was a pretty large effect,” Dr. Peterson said. “It was exciting but also shocking.”

“这是一个非常显著的影响，”彼得森博士说。“这令人激动但也令人震惊。”

While studies suggest that eating earlier in the day is optimal for metabolic health, it does not necessarily mean that you should skip dinner. It might, however, make sense to make your dinners relatively light. One group of researchers in Israel found in studies that overweight adults lost more weight and had greater improvements in blood sugar, insulin and cardiovascular risk factors when they ate a large breakfast, modest lunch and small dinner compared to the opposite: A small breakfast and a large dinner. Dr. Peterson said it confirms an age-old adage: Eat breakfast like a king, lunch like a prince and dinner like a pauper.

尽管研究表明白天更早进食对代谢健康有益，但这并不意味着人们可以不吃晚饭。但是，让你的晚餐相对清淡可能是明智的。以色列的一群研究者在研究中发现，与早餐吃得少、晚餐吃得多相比，当早餐吃得多、午餐吃得适中、晚餐吃得少时，超重的成年人能减少更多的重量，并且在血糖、胰岛素及与心血管疾病相关的因素上大有改善。彼得森博士说，这印证了一句古老的格言：早餐吃得像国王，午餐吃得像王子，晚餐吃得像乞丐。