间歇性断食是什么及如何运作的？

Intermittent Fasting: What is it, and how does it work?
间歇性断食是什么及如何运作的？

Intermittent fasting is an eating plan that switches between fasting and eating on a regular schedule. Research shows that intermittent fasting is a way to manage your weight and prevent — or even reverse — some forms of disease. But how do you do it? And is it safe?

间歇性断食是一种饮食计划，定期在进食和断食之间切换。研究表明，这种方式有助于控制体重，甚至可能预防或逆转某些疾病。那么，具体怎么操作？它安全吗？

What is intermittent fasting?
什么是间歇性断食？

Many diets focus on what to eat, but intermittent fasting is all about when you eat.

With intermittent fasting, you only eat during a specific time. Research shows fasting for a certain number of hours each day or eating just one meal a couple days a week may have health benefits.

Johns Hopkins neuroscientist Mark Mattson has studied intermittent fasting for 25 years. He says our bodies have evolved to be able to go without food for many hours, or even several days or longer. In prehistoric times, before humans learned to farm, they were hunters and gatherers who evolved to survive — and thrive — for long periods without eating. They had to: It took a lot of time and energy to hunt game and gather nuts and berries.

Experts note that even 50 years ago, it was easier to maintain a healthy weight in the United States. There were no computers, and TV shows turned off at 11 p.m.; people stopped eating because they went to bed. Portions were much smaller. More people worked and played outside and, in general, got more exercise.

With internet, TV and other entertainment available 24/7, many adults and children stay awake for longer hours to watch TV, scroll through social media, play games and chat online. That can mean sitting and snacking all day — and most of the night.

Extra calories and less activity can mean a higher risk of obesity, type 2 diabetes, heart disease and other illnesses. Scientific studies are showing that intermittent fasting may help reverse these trends.

大多数饮食关注吃什么，间歇性断食则注重什么时候吃。

间歇性断食要求在特定时间段进食。研究表明，每天断食几个小时或每周几天只吃一顿饭可能有健康益处。

约翰霍普金斯大学神经科学家马克·马特森研究间歇性断食已有25年。他指出，人体已经进化到能长时间甚至几天不吃东西。史前时期，人类以狩猎采集为生，常常要经历长时间的饥饿。

专家还提到，50年前，保持健康体重相对容易。当时没有电脑，电视节目也在11点结束，人们会早睡，饭量较小，户外活动更多。

如今，网络和电视24小时开放，许多人熬夜观看、刷社交媒体或玩游戏。这导致摄入更多热量，活动减少，增加了肥胖、2型糖尿病和心脏病等风险。研究表明，间歇性断食可能帮助逆转这些趋势。

How does intermittent fasting work?
间歇性断食如何运作？

There are several different ways to do intermittent fasting, but they are all based on choosing regular time periods to eat and fast. For instance, you might try eating only during an eight-hour period each day and fast for the remainder. Or you might choose to eat only one meal a day two days a week. There are many different intermittent fasting schedules.

Mattson says that after hours without food, the body exhausts its sugar stores and starts burning fat. He refers to this as metabolic switching.

“Intermittent fasting contrasts with the normal eating pattern for most Americans, who eat throughout their waking hours,” Mattson says. “If someone is eating three meals a day, plus snacks, and they’re not exercising, then every time they eat, they’re running on those calories and not burning their fat stores.”

Intermittent fasting works by prolonging the period when your body has burned through the calories consumed during your last meal and begins burning fat.

间歇性断食的方式多种多样，核心是定期选择进食和断食的时间。例如，每天只在8小时内进食，剩余时间断食，或每周两天只吃一顿饭。

马特森指出，断食数小时后，身体会耗尽糖原，开始燃烧脂肪，这被称为代谢切换。

“间歇性断食与大多数美国人的饮食方式相反，”马特森说。“如果一个人每天三餐再加上零食，并且不运动，他们消耗的只是食物热量，而不是体内的脂肪。”

间歇性断食通过延长燃烧脂肪的时间来起效。

Intermittent Fasting Plans
间歇性断食计划

It’s important to check with your doctor before starting intermittent fasting. Once you get his or her go-ahead, the actual practice is simple. You can pick a daily approach, which restricts daily eating to one six- to eight-hour period each day. For instance, you may choose to try 16/8 fasting: eating for eight hours and fasting for 16.

Although some people find it easy to stick with this pattern over the long term, one research study that was not designed specifically to look at an intermittent fasting pattern found that limiting your daily time window of eating does not prevent weight gain over time or yield significant weight loss results. That study’s results showed that reducing the number of large meals or eating more small meals may be associated with minimizing weight gain or even with weight loss over time.

Another intermittent fasting plan, known as the 5:2 approach, involves eating regularly five days a week. For the other two days, you limit yourself to one 500–600 calorie meal. An example would be if you chose to eat normally on every day of the week except Mondays and Thursdays, which would be your one-meal days.

Longer periods without food, such as 24-, 36-, 48- and 72-hour fasting periods, are not necessarily better for you, and may be dangerous. Going too long without eating might actually encourage your body to start storing more fat in response to starvation.

Mattson’s research shows that it can take two to four weeks before the body becomes accustomed to intermittent fasting. You might feel hungry or cranky while you’re getting used to the new routine. But, he observes, research subjects who make it through the adjustment period tend to stick with the plan because they notice they feel better.

开始间歇性断食前，最好咨询医生。一旦获得许可，执行起来很简单。你可以选择每日进食6到8小时，如16/8断食法，即8小时进食，16小时断食。

有些人长期坚持这种方式，但研究发现，仅缩短每日进食时间并未显著减重。减少大餐或吃小餐可能更有助于减重或防止体重增加。

另一种常见方式是5:2方案，每周五天正常进食，两天只吃一顿500-600卡路里的餐。

更长时间的断食（如24、36、48或72小时）不一定更好，甚至可能有危险，过长时间不吃反而可能让身体储存更多脂肪。

马特森的研究表明，身体需要两到四周适应间歇性断食。在适应期内，你可能会感到饥饿或易怒，但一旦适应，许多人会继续坚持，因为他们感觉更好。

What can I eat while intermittent fasting?
间歇性断食期间可以吃什么？

During the times when you’re not eating, water and zero-calorie beverages such as black coffee and tea are permitted.

During your eating periods, “eating normally” does not mean going crazy. Research shows that you’re not likely to lose weight or get healthier if you pack your feeding times with high-calorie junk food, super-sized fried items and treats.

But what some experts like about intermittent fasting is that it allows for a range of different foods to be eaten — and enjoyed. Sharing good, nutritious food with others and savoring the mealtime experience adds satisfaction and supports good health.

Most nutrition experts regard the Mediterranean diet as a good blueprint of what to eat, whether you’re trying intermittent fasting or not. You can hardly go wrong when you pick leafy greens, healthy fats, lean protein and complex, unrefined carbohydrates such as whole grains.

在断食期间，可以喝水和不含热量的饮料，如黑咖啡或茶。

进食期间也不应放纵，吃太多垃圾食品无法达到减重效果。专家建议摄入营养丰富的食物，比如绿叶蔬菜、健康脂肪、瘦蛋白质和全谷物等。

Intermittent Fasting Benefits
间歇性断食的益处

Research shows that the intermittent fasting periods do more than burn fat. Mattson explains, “When changes occur with this metabolic switch, it affects the body and brain.”

One of Mattson’s studies published in the New England Journal of Medicine revealed data about a range of health benefits associated with the practice. These include a longer life, a leaner body and a sharper mind.

“Many things happen during intermittent fasting that can protect organs against chronic diseases like type 2 diabetes, heart disease, age-related neurodegenerative disorders, even inflammatory bowel disease and many cancers,” he says.

Here are some intermittent fasting benefits research has revealed so far:

• Thinking and memory. Studies discovered that intermittent fasting boosts working memory in animals and verbal memory in adult humans.
• Heart health. Intermittent fasting improved blood pressure and resting heart rates as well as other heart-related measurements.
• Physical performance. Young men who fasted for 16 hours showed fat loss while maintaining muscle mass. Mice who were fed on alternate days showed better endurance in running.
• Type 2 diabetes and obesity. In animal studies, intermittent fasting prevented obesity. And, in six brief studies, obese adult humans lost weight through intermittent fasting. People with type 2 diabetes may benefit: Most of the available research shows that intermittent fasting can help people lose body weight and lower their levels of fasting glucose, fasting insulin and leptin while reducing insulin resistance, decreasing levels of leptin and increasing levels of adiponectin. Certain studies found that some patients practicing intermittent fasting with supervision by their doctors were able to reverse their need for insulin therapy.
• Tissue health. In animals, intermittent fasting reduced tissue damage in surgery and improved results.

间歇性断食不仅能帮助燃烧脂肪，还对身体和大脑有广泛的好处。

马特森的研究显示，间歇性断食带来了诸多健康益处，包括延长寿命、保持苗条身材和增强思维能力。

间歇性断食的具体益处包括：

• 记忆与思维：间歇性断食增强了动物的工作记忆和成人的语言记忆。
• 心脏健康：间歇性断食改善了血压、静息心率等指标。
• 身体表现：16小时断食的年轻男性减脂而保持肌肉，小鼠则表现出更好的跑步耐力。
• 2型糖尿病与肥胖：动物研究表明，间歇性断食预防了肥胖。在短期研究中，肥胖成人通过间歇性断食减轻了体重。研究还显示，它有助于降低糖尿病患者的血糖、胰岛素和瘦素水平。
• 组织健康：动物研究表明，间歇性断食减少了手术中的组织损伤，并提高了手术结果。 

Is intermittent fasting safe?
间歇性断食是否安全？

Some people try intermitting fasting for weight management, and others use the method to address chronic conditions such as irritable bowel syndrome, high cholesterol or arthritis. But intermittent fasting isn’t for everyone.

Before you try intermittent fasting (or any diet), you should check in with your primary care practitioner first. Some people should steer clear of trying intermittent fasting:

• Children and teens under age 18.
• Women who are pregnant or breastfeeding.
• People with type 1 diabetes who take insulin. While an increasing number of clinical trials have shown that intermittent fasting is safe in people with type 2 diabetes, there have been no studies in people with type I diabetes. Mattson explains, “Because those with type I diabetes take insulin, there is a concern that an intermittent fasting eating pattern may result in unsafe levels of hypoglycemia during the fasting period.”
• Those with a history of eating disorders.

But people not in these categories who can do intermittent fasting safely can continue the regimen indefinitely. It can be a lifestyle change ― and one with benefits.

Keep in mind that intermittent fasting may have different effects on different people. Talk to your doctor if you start experiencing unusual anxiety, headaches, nausea or other symptoms after you start intermittent fasting.

一些人通过间歇性断食管理体重，另一些人则用它来应对慢性病。但这并不适合所有人。

开始前，最好先咨询医生。以下人群不适合间歇性断食：

• 18岁以下的儿童和青少年。怀孕或哺乳期的女性。
• 1型糖尿病患者。尽管越来越多的研究表明，间歇性断食对2型糖尿病患者是安全的，但1型糖尿病患者可能在断食期间发生低血糖。
• 有饮食失调史的人。

但对于健康人群，间歇性断食可以成为一种长期的生活方式，并带来好处。

如果在断食期间感到异常的焦虑、头痛或恶心，请及时就医。

编译自 Intermittent Fasting: What is it, and how does it work?。