Fasting: Safe for Your Health or Just a Diet Fad?

Jessica Thiefels, The Upside Blog by

by | Read time: 4 minutes

Fasting gets a bad reputation thanks to poor health advice and extreme fasting diets that become popular overnight, like the Master Cleanse juice fast. However, fasting has been a staple of the human diet for centuries, dating back to the 1800s when E.H. Dewey wrote “The True Science of Living,” which said: “Every disease that afflicts mankind [develops from] more or less habitual eating in excess of the supply of gastric juices.”

He tested his theories on Charles Haskell who was “miraculously” cured by fasting, according to “Fasting: The History, Pathophysiology and Complications.”

Fast-forward to the modern world where people are eating more than ever before, with the average world consumption per person being 2,870 calories daily (and more than 3,600 in just the U.S.).

Woman on Fasting Diet Making Fresh Green Juice |

Fasting advocates for a different style of eating that reduces the amount of food we put in our bodies. Fasting allows us to return to a more traditional way of eating—it’s safe to say our ancestors weren’t eating three large meals and two to three snacks a day.

While there’s nothing wrong with multiple meals and snacks per day, there is something to be said for fasting one to two days a week for set period of time.

Here’s what you need to know, including safety tips, before you try your first fast:

Types of fasting

A safe fast will not require you to go without food for days at a time. This is unhealthy because our bodies need fuel to think and stay active. Consider the style of each fast and choose one that will best fit your lifestyle.

Alternate-day fasting: This type of fasting, made popular by James Johnson’s book “The Alternate-Day Diet,” promotes weight loss by turning the SIRT1 gene on and off. This fasting routine is split between “up days” and “down days.” The down days, when intake is limited, are when the SIRT1 gene is activated, promoting weight loss. On up days, you consume normal calorie intake. If you choose to follow this plan, use Johnson’s calorie counter to determine your specific caloric intake for your down days.

Eat-Stop-Eat: With this style of fasting, you fast for 24 hours one to two days each week. Brad Pilon, author of “Eat Stop Eat,” says that this form of fasting is often easier than standard diet because you don’t have of think about what you should or shouldn’t eat every few hours.”

5:2 fast diet: You’ll have a restricted calorie intake, 500 to 600 calories, on two non-consecutive days of the week. This gives you a much-needed reprieve from the fasting, and as your body adjusts, the low-calorie days will get easier to manage.

16/8 method: Also called the Leangains protocol, 16/8 fasting requires you to ideally skip breakfast and then eat for just eight hours of the day. Leangains creator, Martin Berkhan, suggests, “My general position on the fasted phase is that it should last through the night and during the morning hours. Ideally the fast should then be broken at noon or shortly thereafter if you arise at 6-7 a.m. like most people. Afternoons and evenings are usually spent in the fed state.”

Regardless of the type of fast you choose, the benefits remain similar across the board, including:

The one drawback everyone’s talking about…

There are many benefits to fasting, including one not mentioned above: understanding your body’s hunger cues. When you can’t eat, you won’t snack out of boredom. You’ll also be extremely aware of your hunger when you can’t eat and your body is asking for food. In a society that promotes regular snacking, it’s easy to forget how to interpret we’re hungry and when we’re just bored.

The No. 1 drawback, however, is hunger. Almost every study we read expressed concern with hunger being a deterrent for the success of safe fasting as a sustainable and realistic health approach. Who wants to stick with a lifestyle change that leaves them hungry most of the day? To avoid this issue, keep a few things in mind:

  1. Your body will get used to the change in eating tempo, and as it adjusts, your regular hunger pangs will likely decrease. Soon, this style of fueling will become as normal as having three meals a day.
  2. Choose nutritionally dense foods every time you eat: lean protein like salmon and chicken; high-fat foods like avocado and nuts; and high-fiber foods like oatmeal, sweet potato and kale.
  3. Eat mindfully. If you eat while you’re working, chatting on the phone or watching television, you’re not paying attention to the food that you’re eating. As such, it can be less satisfying, leaving you to feel less full.

So is it time to fast?

Any lifestyle change has to work for what you need in your life right now. Test one of the fasting options for just one week to gauge how you feel and evaluate how it works for your schedule. Then give it one more week to see if issues with hunger can be ironed out with some of the above tips. If one type of fast doesn’t work for you, but you still want to reap the benefits, try another one. With a variety of styles and options, you’re bound to find one that makes you feel great and helps you reach your health goals.