What is Intermittent Fasting, And Does It Work?

Intermittent fasting is an eating plan that switches between fasting and eating on a regular schedule. Research has shown that intermittent fasting is a way to manage weight and prevent — or even reverse — some forms of disease.

There are many diets that focus on what to eat, but intermittent fasting is all about when you eat. In a nutshell, intermittent fasting dictates that you only eat during a specific time. Fasting for a certain number of hours each day or eating just one meal a couple days a week can help the body burn fat. And scientific evidence points to some health benefits as well.

There are many diets that focus on what to eat, but intermittent fasting is all about when you eat.

According to Johns Hopkins neuroscientist Mark Mattson, Ph.D., who has studied intermittent fasting for 25 years, our bodies have evolved to be able to go without food for many hours, sometimes even several days. 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.

In prehistoric times, before humans learned to farm, they were hunters and gatherers who evolved to survive — and thrive — for long periods without eating.

How does intermittent fasting work?

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 that are suited for different age groups and lifestyles.

According to Mattson, after hours without food, the body exhausts its sugar stores and starts burning fat. He refers to this as metabolic switching. Intermittent fasting works by prolonging the period when the body has burned through the calories consumed during your last meal and begins burning fat.

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

Intermittent Fasting Plans

It’s important to check with your doctor before starting intermittent fasting. Once you get the go-ahead, the actual practice is simple. 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. To make it very practical, you could have your last meal at 7pm and then start eating again at 11am next day.

Another approach, 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.

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

You may choose to try 16/8 fasting: eating for eight hours and fasting for 16. Another, known as the 5:2 approach, involves eating regularly five days a week.

What can one eat while intermittent fasting?

During the times while not eating, water and zero-calorie beverages such as black coffee and tea are permitted. And during eating periods, “eating normally” does not mean going crazy. One is not likely to lose weight or get healthier if feeding times are packed with high-calorie junk food such as fried items and sweet treats.

What benefits of Intermittent Fasting are backed by science?

Research shows that the intermittent fasting periods do more than burn fat. Data has revealed a range of health benefits associated with the practice. These include a longer life, a leaner body and a sharper mind.

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

• Longevity. As humans have a long lifespan, longevity research is usually first conducted on mice. A recent study from October 2021 by Lamming et. al. showed that fasting improved the lifespan of male mice by half a year (or 25%). The study also showed that “eating less” didn’t contribute to lifespan extensions. They concluded we are “when we eat” and not “what we eat”.

• 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.

• Diabetes and obesity. In animal studies, intermittent fasting prevented obesity. And in six brief studies, obese adult humans lost weight through intermittent fasting.

• Tissue health. In animals, intermittent fasting reduced tissue damage in surgery and improved results.

Data has revealed a range of health benefits associated with intermittent fasting. These include a longer life, a leaner body and a sharper mind.

Is intermittent fasting safe?

Some people try intermittent 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.

Some people who should steer clear of trying intermittent fasting include:

• Children and teens under age 18.

• Women who are pregnant or breastfeeding.

• People with diabetes or blood sugar problems.

• Those with a history of eating disorders.

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