What Is Intermittent Fasting? Explained in Simple Terms (2024)

Intermittent fasting involves alternating cycles of eating and going without food. Depending on the type, you may try intermittent fasting at different times of day and change how many calories you eat.

Intermittent fasting is currently one of the world’s most popular health and fitness trends.

Research shows that this different type of eating pattern can help you with weight loss, improve metabolic health, manage stress, help protect against disease and other conditions, and perhaps even help you live longer.

This article explains what intermittent fasting is and why you should care.

What is intermittent fasting?

Intermittent fasting is an eating pattern where you cycle between periods of eating and fasting.

It does not say anything about which foods to eat, but rather when you should eat them.

There are several different intermittent fasting methods, all of which split the day or week into eating periods and fasting periods.

Most people already “fast” every day, while they sleep. But intermittent fasting as a way of eating is different and can be quite simple. This may include:

  • extending your sleeping fast a little longer
  • skipping breakfast
  • eating your first meal at noon
  • eating your last meal at 8 pm

Anecdotally, many people report feeling better and having more energy during a fast. But other people report feeling worse and less energic.

Hunger is common but tends to be more of an issue for people who follow a pattern of fasting for an entire day, multiple times per week.

No food is allowed during the fasting period, but you can drink water, coffee, tea, and other noncaloric beverages.

Some forms of intermittent fasting allow small amounts of low calorie foods during the fasting period.

Taking supplements is generally allowed while fasting, as long as there are no calories in them.

History of fasting at a glance

Humans have been fasting for thousands of years.

Sometimes, it was done out of necessity when there wasn’t any food available.

In other instances, it was done for religious reasons. Various religions, including Islam, Christianity, and Buddhism, mandate some form of fasting.

There’s nothing “unnatural” about fasting, and our bodies are well-equipped to handle short periods of not eating.

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How does fasting benefit your health?

All sorts of processes in the body change when we don’t eat for a while, in order to allow our bodies to survive during a period of famine. This relates to how our bodies work with hormones, genes, and important cellular repair processes.

You can experience reductions in blood sugar and insulin levels when fasting. It can also lead to an increase in human growth hormone, an important hormone produced by your pituitary gland that helps regulate growth in children and also improves muscle growth, strength, and lean body mass.

But there are other health benefits, too.

Can intermittent fasting help with weight loss?

Many people do intermittent fasting to lose weight, as it’s an effective way to restrict calories and burn fat.

Others do it for metabolic health benefits, as it can improve various risk factors and health markers.

Does intermittent fasting help protect against other diseases and conditions?

Some research also suggests that it may help protect against other health conditions and diseases.

These may include:

  • heart disease
  • type 2 diabetes
  • cancer
  • Alzheimer’s disease

But more clinical research is needed to determine how intermittent fasting might protect against different diseases and health conditions.

Fasting may help you live longer

There’s also some evidence that intermittent fasting can help you live longer. Some studies also show that it may extend your life as effectively as calorie restriction.

A 2021 clinical research shows that even mild intermittent fasting — along with healthy nutrition, movement, sleep patterns, and stress management — could help you live longer (decrease your biological age, per the study) by a little more than 3 years.

Intermittent fasting has become trendy in the past few years. You can try different types or methods to change the duration and timing of your daily fasting hours.

Here are some of the most popular ones:

  • The 16/8 Method: You have a fixed window of eating 8 hours each day. You don’t eat any food for the remaining 16 hours, but you can drink water, plain coffee, or tea. Read more here.
  • The 5:2 Diet: During 2 days of the week, eat only about 500–600 calories. For the other 5 days of the week, you eat as usual and don’t have to think about restricting calories.
  • Eat-Stop-Eat: Once or twice a week, don’t eat anything from dinner one day until dinner the next day (a 24-hour fast).

There are many other variations, as well.

You can read more here about specific tips that can help you decide on and follow an intermittent fasting schedule.

This type of intermittent eating and not eating isn’t for everyone.

You may experience mood swings, hunger, and challenges in finding the best routine when trying out intermittent fasting and deciding on a schedule that works for you.

Certain meal plans and fasting methods may work better for some people versus others. Talking with your healthcare team and nutritionist or dietician (if you have access to one) may be a good first step in determining what might work best for you.

You can read more here about the pros and cons of intermittent fasting.

Takeaway

As long as you stick to healthy foods, restricting your eating window and fasting from time to time can have some good health benefits. It’s an effective way to lose fat and improve metabolic health, while simplifying your life at the same time.

What Is Intermittent Fasting? Explained in Simple Terms (2024)

FAQs

What is the simple way to explain intermittent fasting? ›

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.

What are the basic rules for intermittent fasting? ›

Common interpretations of this eating style include:
  • Eating during a 12-hour window every day (between 7 a.m. and 7 p.m., for example) and fasting for the other 12 hours.
  • Eating during an 8-hour window every day (between 11 a.m. and 7 p.m., for example) and fasting for the other 16 hours.
Dec 30, 2021

What are the full details of intermittent fasting? ›

Intermittent fasting means that you don't eat for a period of time each day or week. Some popular approaches to intermittent fasting include: Alternate-day fasting. Eat a normal diet one day and either completely fast or have one small meal (less than 500 calories) the next day.

What is fasting simply explained? ›

Simply put, it means you stop eating completely, or almost completely, for a certain stretch of time. A fast usually lasts from 12 to 24 hours, but some types continue for days at a time. In some cases, you may be allowed water, tea, and coffee or even a small amount of food during the “fasting period.”

What foods should you avoid during intermittent fasting? ›

Examples of foods and drinks you should avoid while intermittent fasting include:
  • Candy.
  • Cookies.
  • Chips.
  • Fruit drinks.
  • Soda.
  • Sweetened coffee and tea.
  • Sugary cereals.

What foods won't break a fast? ›

Foods you can eat while fasting
  • Water. Plain or carbonated water contains no calories and will keep you hydrated during a fast.
  • Coffee and tea. These should mostly be consumed without added sugar, milk, or cream. ...
  • Diluted apple cider vinegar. ...
  • Healthy fats. ...
  • Bone broth.

What are the best hours for intermittent fasting? ›

Depending on your lifestyle and when you can manage to stop eating, the best hours for intermittent fasting include the 16/8 or 14/10 fasting periods. Intermittent fasting is hailed by many as the new mantra of weight loss, disease prevention, and reversal of aging.

How much weight can you lose in a month with intermittent fasting? ›

If you consistently stay active while following intermittent fasting, you can lose as much as 6-8 pounds per month. This estimation is shockingly high when you consider that all you have to do is not eat for select hours throughout the day.

Can I eat whatever I want while intermittent fasting and still lose weight? ›

It's not a diet, so unless you have individual dietary restrictions, you can eat whatever you want within the eight-hour time frame. But the plan will work best for weight loss if you are already making smart, nutrient-rich choices, said NBC News health and nutrition editor Madelyn Fernstrom, Ph.D.

What is the best intermittent fasting window to lose belly fat? ›

Best Intermittent Fasting Method For Visceral Belly Fat

14/10 Method: Fast for 14 hours and have a 10-hour eating window daily. That means you restrict your food intake to a specific 10-hour period while abstaining from caloric consumption for the remaining 14 hours.

What happens after 1 month of intermittent fasting? ›

Intermittent fasting has been shown to improve insulin sensitivity, reduce blood sugar levels, and lower the risk of developing type 2 diabetes. In addition, after one month of intermittent fasting, you may notice improved metabolic health and reduced risk of chronic diseases.

What can I drink in the morning while intermittent fasting? ›

Generally speaking, while fasting with time-restricted intermittent eating, you don't eat any food at all and only drink beverages with very few calories, such as water or unsweetened coffee and tea without milk. When you're not fasting, it's important to eat a healthy and varied diet that's good for your body.

Why am I not losing weight on 16:8 fasting? ›

If you've tried intermittent fasting but aren't losing weight, possible reasons why include overeating during your eating window and poor food choices. To help, you can try eating fewer calories, work on balancing your meals, or create a smaller or larger eating window.

Does coffee break a fast? ›

The bottom line. You can drink moderate amounts of black coffee during fasting periods, as it contains very few calories and is unlikely to break your fast. In fact, coffee may enhance the benefits of intermittent fasting, which include reduced inflammation and improved brain function.

Why is 16 hours the magic number for fasting? ›

While both 12-hour and 16-hour fasting can promote fat burning, it's possible that a 16-hour fast may be more effective. This is because the longer fasting period may lead to a greater depletion of glycogen stores, which can trigger higher levels of fat burning.

Is it better to fast 12 or 16 hours? ›

If weight loss is a primary goal, a 16-hour fast may be more effective. However, if you're looking for a more sustainable fasting routine, a 12-hour fast may be a better fit. Ultimately, the best fast duration for you is the one that meets your needs and is something you can achieve.

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