Intermittent Fasting 101: What It Is and How to Do It

Fajita-Style New York Strip Steaks

The Spruce / Ali Redmond

A Note From the Editors

The Spruce Eats does not endorse this diet; rather, we are providing some information that can contribute to your decision. 在对你的饮食做出任何重大改变之前,请和你的医生或注册营养师谈谈.

Intermittent Fasting Basics

While Intermittent Fasting may sound like a new trend, 几个世纪以来,人类为了健康和精神原因而禁食. And we've been studying the health effects for a long time. For example, in the early twentieth century, doctors studied long-term fasting as a treatment for diabetes. More recently, 研究揭示了更短的禁食间隔的好处,也就是ca88会员登录入口现在所说的间歇性禁食, or IF.

Intermittent fasting isn’t about what you eat, it’s about when. With no calorie cap or special foods to make or buy, IF is more of a lifestyle than a prescriptive diet. There are several types of IF, 包括限时饮食——在指定的时间内吃完一天的食物——和不吃, or very little, food for entire days. Here are some of the most common IF plans.

16:8 On this plan, you consume only calorie-free beverages for 16 hours, and then you eat during an eight-hour period of your choosing. (同样适用于20:4养生法,这是一种ca88会员登录入口不推荐的极端饮食计划.)  

5:2 这个计划包括你通常一周吃五天的食物. 在另外两天(最好是非连续的),你要把你的摄入量减少到你每天典型热量的25%(女性约500卡路里,男性约600卡路里). On a similar program called Alternate Day Fasting (ADF) you consume only calorie-free beverages every other day of the week; on the alternate days you eat your as usual. 

The goal of IF is to lower your insulin levels. Eating raises insulin levels in the blood. 这有助于消化过程中产生的葡萄糖进入细胞,以满足能量需求.  禁食超过12小时会抑制胰岛素分泌,促使身体燃烧储存的脂肪, creating ketones that cells can also use for energy.

Weight loss and reduced body fat typically attract people to IF, but this way of eating may also improve energy, reduce blood glucose levels, tamp down inflammation, lower blood pressure, improve cardiovascular health, and slow the aging process.

Pros and Cons of Intermittent Fasting


  • You get to choose the IF style that works best for you.
  • It’s possible to shed pounds without counting calories. 一项针对只在上午10点到下午6点吃东西的肥胖人群的研究, without tracking what they ate, consumed an average of 350 fewer calories daily, lost about 3 percent of their body weight, and lowered their blood pressure during a 12-week period.
  • 定期实现酮症可以减少体内脂肪储存,从而使身体更瘦.
  • 缩短进食时间的人白天睡得更好,也更清醒.
  • 如果你吃得少了,“如果”就能节省购物和准备食物的时间,还能降低食物成本.
  • 5:2计划可能适用于那些发现一周中有两天严格控制饮食更容易的人, or who like to eat whatever they want on the weekends, or both. 
  • Because of its effect on cholesterol, insulin, and glucose levels in the blood, IF may help protect against diabetes and cardiovascular disease.


  • 禁食会让你感到神经过敏、暴躁易怒,还可能导致头痛. 
  • 整天不吃东西很难满足营养需求. 多种维生素和其他单一维生素和矿物质补充剂有助于填补各种IF中微量营养素的膳食缺口, but you may come up short on protein, healthy fats, and fiber.   
  • 对吃饭时间的过分关注会加剧现有的对食物的焦虑, or create new ones, such as obsessing about eating. 
  • Exercise reduces glucose and insulin levels, and you may need to change the intensity, and timing, of your exercise routine to prevent fatigue. 
  • 和孩子一起生活并照顾孩子的成年人——这一群体需要稳定的营养供应——可能会向孩子们传递关于食物的矛盾信息. 
  • Depending on the length and timing of the eating window, IF可能会影响家庭和与食物有关的社交活动. 
  • IF is not always more beneficial than daily calorie restriction. 一项为期一年的研究发现,ADF的减肥效果与将卡路里摄入量减少25%的效果相同.

Common Intermittent Fasting Mistakes

Lack of consistency. 你需要有规律的禁食计划来充分抑制胰岛素水平和促进脂肪燃烧. Pick a pattern and stick to it, including on weekends. 

Eating too much at night. Our bodies are designed to process food better during the day. 吃到晚上8点或9点可能会降低限时饮食计划的有效性.  In a study of women, 那些在下午3点前摄入大部分卡路里的人比那些在下午3点后摄入大部分食物的人减掉的体重多30%, despite eating a similar number of calories

Not easing into IF. If you want to do a plan like 16:8, start by fasting for 12 hours. 然后,在接下来的几天里逐渐增加这段时间,逐步达到你的目标. 

Who Should Not Do Intermittent Fasting

Certain groups need a steady flow of nutrients for good health. 虽然不吃东西对很多人来说是安全的,但如果:

  • You’re under 18 and over 75
  • Pregnant or breastfeeding 
  • 你服用降压药或需要在一天的特定时间与食物一起服用药物
  • You’re an endurance athlete
  • 你有慢性疾病,包括肾病、1型或2型糖尿病 
  • You have a history of disordered eating
How to Start to Intermittent Fasting

The Spruce / Ellen Lindner

What to Eat

No food is off-limits on any IF regimen. However, 均衡的饮食计划对于获取身体所需的营养是很重要的, and even more so if you are eating less overall. Include adequate protein, fiber, and healthy fats at every meal, 每天吃三份低脂乳制品和至少五份水果和蔬菜来帮助你保持营养和饱腹感, and to limit cravings for salty or sweet low-nutrient foods. If you want treats, enjoy small portions within your eating time-frame. 

What Not to Eat

While you can include any food on IF, avoid an eating free-for-all mindset during your eating window, 会导致体重增加,并抵消其他潜在的IF益处. 选择令人满意的、有营养的、能控制饥饿感的食物,并定期食用. 

Bottom Line

During intermittent fasting, you focus more on the clock than on calories, and every type of food is allowed. 指定的时间可能会让人们更容易控制他们的食物摄入, especially in the evening.  Certain groups should not try IF, 但只要你摄入足够的卡路里,满足你的营养需求, and IF doesn’t interfere with your mental health, or your work, family, or social life, it’s probably safe and sustainable. If going long stretches without eating isn’t appealing, 更短的每日饮食窗口可能提供类似于更激烈的IF计划的好处.

Article Sources
The Spruce Eats uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process 了解更多ca88手机版登录如何进行事实核查,并保持ca88会员登录入口的内容准确、可靠和值得信赖.
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