Fasting may have landed in the limelight only recently, but the practice itself goes back as far as human history, with roots in our prehistoric lifestyle and manifestations in spiritual and medicinal practices from all over the world.

While many people are incorporating fasting into their lives as a tool for weight loss, it also has serious benefits in other aspects of life. In fact, many studies have shown that regular fasting can help us live longer, healthier lives.

What is Fasting?

Fasting simply means to abstain from food and drink for a set amount of time. It can either involve a complete fast — avoiding eating and drinking altogether — or a partial fast, where only certain foods and beverages are allowed.

A fast typically lasts between 16-72 hours, with some people taking on extended fasts that can stretch for weeks or months.

Fasting is an ancient practice that is found in many traditions around the world. In Islam, Muslims fast from sunrise to sunset for the entire month of Ramadan. In Judaism, Jews fast for up to 25 hours leading up to Yom Kippur. Christians also have a tradition of fasting, with many abstaining from meat on Fridays.

Benefits of Fasting

Fasting practices can be found all over the world, and they are integrated with many different aspects of life. Science is increasingly showing that fasting has a wide range of health benefits. It can play a pivotal role in longevity, preventing neurodegenerative diseases, fighting off cancer and, of course, in losing weight.

Lose Weight

One of the main reasons fasting is gaining popularity so rapidly is its weight-loss benefits. According to scientific literature, intermittent fasting can be just as effective as calorie restriction and potentially increases your metabolism!

Anecdotally, people who’ve tried fasting diets often find it helps to give them more agency over their eating habits by learning not to give into their cravings.

Reduce Insulin Resistance

Insulin plays a key role in taking the sugar from carbohydrates and either turning it into energy or storing it for later use. When your body becomes resistant to insulin, it has to produce more of it to have the same effect and higher levels of insulin are associated with chronic diseases, heart disease, and even cancer.

Studies have shown that intermittent fasting and alternate-day fasting can reduce your insulin resistance and decrease your blood sugar levels.

Fight Inflammation

While inflammation is the body’s natural response to problems, chronic inflammation is increasingly coming to the forefront as a common factor in many diseases. Chronic inflammation is also associated with obesity as a result of the metabolic stress the body undergoes. But don’t worry! There’s evidence that fasting can help reduce the level of inflammation within your body.

Delay Aging

Fasting and fasting mimicking diets have been proven to reduce age markers and risk factors for aging and aging related diseases. A series of promising animal studies have been done on fasting, including one that found that rats that fasted every other day lived 83% longer than rats who didn’t.

Studies have also found that one of the ketones produced when the body enters ketosis (which you may have heard of in terms of another popular diet – the keto diet) helps preserve the circulatory system as well.

Build Your Muscles

Fasting increases the amount of human growth hormone (HGH) in your body. HGH plays a key role in building muscle strength and stimulating the metabolism, and it also helps you lose weight. One small study found that fasting for two-days resulted in a five-fold increase in HGH production. That’s a huge difference for your whole body!

Boost Your Brain

In addition to being great for your body, fasting also has some brain benefits. Fasting has been shown to improve cognition and help prevent neurodegenerative diseases, like Alzheimer’s. Intermittent fasting has also been shown to increase the brain’s supply of brain-derived neurotrophic factor (BDNF), which protects your brain cells and works as an antidepressant.

Different Types of Fasting

Time-Restricted Eating

Known in the scientific community as Time-Restricted Feeding (TRF), this practice involves eating during a certain window of time each day and abstaining from food for the rest of the day. These fasts take the emphasis off of counting calories, which can help promote a healthier relationship with food while still resulting in some pretty phenomenal results.

The 16:8 Method
The most common form of TRF is 16:8, where you eat during an eight-hour window and fast for the other sixteen hours of the day. It gives you the freedom to choose when that feeding window will be. You can opt to skip breakfast and eat from 12pm-8pm or have breakfast and catch a light dinner by eating from 9am-5pm. You can place your feeding window anywhere that works with your schedule.

While you don’t need to count calories, be careful not to overeat when you break your fast and try to do so with nutritious foods!

One Meal a Day (OMAD)
Another method is the One Meal a Day method, or OMAD. This style of time-restricted eating involves fasting for 23 hours and taking in all of your calories during a one hour window. It may sound unconventional, but there’s reason to believe that the ancient Romans also ate only one meal a day. Plus, it’s been shown in studies that undertaking longer daily fasts can help reduce your blood glucose.

Intermittent Fasting (IF)
Intermittent fasting involves alternating days of fasting with feast days. Feast days don’t mean days of binging, though. If you’re using the IF method to lose weight, you’ll want to take your feast days seriously by putting together a healthy diet that’s optimized for your mental and physical health.

The 5:2 Method
5:2 fasting involves eating regularly for five days of the week with two fast days where you cut your daily calories down to a quarter of what you usually eat. For women, this is typically around 500 calories versus around 600 for men. 5:2 diets have been shown to be effective for weight loss and improving insulin sensitivity.

It’s important to note that you won’t have success with this diet if your normal meals are comprised of high-calorie junk foods with low nutritional values. If you want to see real success with any of these diet methods, they need to be paired with a shift to healthier, more nutritious eating.

Extended Fasting

Extended fasts involve fasting for longer than 24 hours. Studies show that fasting between 24-48 hours induces a state of autophagy, which is your body’s natural recycling process. Autophagy is an important part of brain and body health and longevity.

Keep in mind that if you’re considering trying an extended fast, it’s important to check in with a medical professional, as they can be dangerous for persons with health-risks.

Fasting-Mimicking Diets

Another fasting method is a fasting-mimicking diet. While these diets don’t actually involve fasting, they trick your body into thinking it’s in a fasting state so it reacts similarly.

The diets are plant-based and high-fat but low-calorie and low-carb. Studies specifically on this diet have been shown to reduce belly fat, as well as blood sugar and cholesterol There’s a great podcast with the pioneer of fasting-mimicking diets, Doctor Valter Longo, that’s worth a listen if you’re interested in trying this kind of diet.

Fasting Tips

If you want to give fasting a try, or if you’re ready to make the jump to full-time fasting, here are some tips to ease the transition:

  • Stay hydrated. Drinking water won’t break your fast and, in fact, it’s an essential part of the process. Staying hydrated can help you feel less hungry, and since you take in 20-30% of your daily fluids from food, it’s even more important on fast days.
  • Be careful how you break your fasts. Try to avoid binging after a fast just because you’ve gone longer without eating than you’re used to. Feasting after your fast can leave you feeling tired and bloated, or even lead to gastrointestinal issues.
    • Plus, if you break your fasts with huge meals you may be defeating the purpose of fasting by dramatically increasing your calorie intake.
  • Be thoughtful about your diet. On non-fast days or during your feeding windows, it helps to have a healthy diet full of a variety of fresh, wholesome foods. You’ll feel better and think more clearly than if you eat ultra-processed stuff.
  • If you feel sick while fasting, stop. If your fast is causing you to become ill, you should end it. Fasting isn’t for everyone and if you’re having problems, be sure to consult a healthcare provider.
    • One way to help avoid issues is to start with smaller fasts and work your way up if you want to. The most important thing is that there’s no shame in stopping your fast. Your health comes first.