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Fasting Benefits, Types and Tips for Success

By Rachel Link, RD, MS

March 12, 2024

When looking for new ways to lose weight, manage a healthy weight or even help support heart health, fasting is an idea that many of us want to know more about.

These days, there are many different types of fasting to consider. While intermittent fasting remains the most popular kind, there are others that are more traditional or unusual.

Below we walk you through the different fasting types, benefits you could expect, plus how exactly to practice fasting. We also answer some common fasting questions, such as how fasting can be different for women versus men.

As always, though, you should consult your healthcare professional prior to beginning any new dietary or lifestyle regimen, including any form of fasting.

What Is Fasting?

Fasting is a practice that involves abstaining from food for a specific period of time. With most forms of fasting, liquids like water, coffee and tea are usually permitted.

Fasting has been around for thousands of years, with spiritual fasting as a part of many religions. Lately, fasting, in particular intermittent fasting, has become popular for those looking to manage their weight, maintain healthy blood sugar levels already in the normal range and boost their overall health.

In place of three square meals a day or a handful of smaller meals throughout the day, you have a specific window of time when you eat, whether it’s a few hours a day, a certain time of day (such as after sundown) or certain days of the week. During that time, you can eat whatever you want — of course, within reason.

Again, this is just for educational purposes and you should always work with your health professional if you wish to fast in any form.

Types of Fasting

Intermittent Fasting

This type of fasting is also known as cyclic fasting. Intermittent fasting is a catch-all phrase for eating (and not eating) intermittently and usually involves some calorie restriction.

Typical intermittent fast times range from 14 to 18 hours. The longest period any one of these plans indicate abstinence from solid food would be about 32–36 hours.

Intermittent fasting types include:

• 16/8 Fasting: This method requires you to fast for 16 hours every day and limit your eating to an eight-hour window. Typically, this involves not eating anything after dinner and skipping breakfast the next morning. This is the most popular form of intermittent fasting.

• Alternate-Day Fasting: This involves eating every other day. On fasting days, some eat no food at all and others eat a very small amount, usually around 500 calories. On non-fasting days, you follow your usual, healthy diet.

• The Warrior Diet: This diet entails eating only specific foods (such as fruits, vegetables, clear broth and hard-boiled eggs) during the day and eating one large meal at night.

• Eat-Stop-Eat: This variation involves picking one or two days out of the week in which you fast for 24 hours, then eat nothing from dinner one day until dinner the next day. On the remaining days, you follow a regular diet.

• 5:2 Diet: For five days of the week, you eat normally. During the remaining two days, you restrict your caloric intake to between 500–600 calories daily.

• OMAD (One Meal a Day): The OMAD diet is the most extreme type of intermittent fasting. You fast for 23 hours and the eating window is only for one hour. For optimal success, that one hour needs to fall within the same four-hour time block each day.

Time-Restricted Eating

If you practice time-restricted eating, you abstain from food for anywhere between 8–12 hours. Unlike intermittent fasting that typically involves calorie restriction, you can eat as much of your favorite healthy foods as you’d like. This is one of the most common methods of fasting, and many people already practice it without knowing it (such as those people who don’t snack after dinner).

Water Fasting

A water fast, also known as a water diet, is a type of fast that involves drinking only water for a specific period of time. These fasts can last anywhere from 24–72 hours and, like other forms of fasting, food is generally restricted during fasting windows.

People try water fasting for a number of reasons. It is a common practice in many religions and is sometimes used to build faith and focus on spiritual growth. It is also used to prepare for certain medical procedures, including certain blood tests and physical exams.

Dry Fasting

Fasting is a practice that involves abstaining from food for a specific period of time. With most forms of fasting, liquids like water, coffee and tea are usually permitted. However, with dry fasting, all foods and liquids are restricted during the fasting window.

Dry fasting is commonly used in religious or spiritual practices, including Ramadan, a month-long Muslim holiday in which people fast every day from dawn to sunset. Fasting is also thought to improve self-discipline, increase feelings of gratitude and enhance faith and spirituality.

Dirty Fasting

Dirty fasting is one method of fasting (abstaining from eating or drinking anything but water for a period of time) that is a bit more flexible than other methods. It allows you to eat a very limited number of calories while “fasting,” such as about 100 calories or less — such as an apple a day, or just low-calorie drinks.

The Daniel Fast

Based off of Daniel’s experiences in the Bible’s Book of Daniel, the Daniel fast is a partial fast where vegetables, fruits and other healthy whole foods are featured prominently, but meat, dairy, grains (unless they’re sprouted ancient grains) and drinks like coffee, alcohol and juice are avoided.

Potential Health Benefits

1. Promotes Healthy Weight Management

Many people turn to fasting for how to help lose weight or promote healthy weight management, and for good reason. When your body runs out of glucose (sugar) to use for energy, it will begin breaking down glycogen stores instead. After the glycogen stores are depleted, it starts converting fat into ketones, which can be used as an alternative fuel source for the body (ketosis).

Ketosis is a metabolic state in which your body uses fat for fuel instead of sugar. Fasting works by depriving your body of its main source of energy, forcing it to start breaking down fat cells instead.

Intermittent fasting works, too. Not only does it help reduce your overall caloric intake by restricting your eating window, but it can also rev up fat-burning by pushing your body into ketosis.

2. Maintains Heart Health

Studies indicate that fasting can positively influence heart health factors, including supporting healthy cholesterol levels and triglycerides.

It may also support a healthy response to inflammation, another major factor that can benefit a healthy heart.

3. Supports Already-Healthy Blood Sugar Levels in the Normal Range

Fasting is a great tool for supporting already-healthy blood sugar levels in the normal range. Plus, it can also help support healthy insulin levels, which can benefit the body’s ability to use this important hormone efficiently in its normal function of transporting sugar from the bloodstream to the cells.

4. Supports a Healthy Response to Inflammation

Inflammation is a normal immune system response designed to protect the body against injury and more. It needs to be balanced, though, which is why it’s important to promote a healthy response to inflammation.

Promising research suggests that fasting may help support a healthy response to inflammation. Plus, it can also support a healthy response to reduce oxidative stress throughout the body.

5. Promotes Normal Secretion of HGH for Muscle Gains

Studies indicate that fasting can significantly increase human growth hormone (HGH) levels. A recent study with 47 people concluded that there was up to a five-fold increase in HGH levels during a 24-hour fast. Of course, more studies need to be conducted to be conclusive.

HGH is naturally produced by the body but remains active in the bloodstream for just a few minutes. It’s been effective in helping with healthy weight management and muscle building.

6. Helps with Hunger Pangs and Satiety

Known as the hunger hormone, ghrelin is responsible for telling your body that it is hungry. Ideally levels remain low, such as after a long sleep. While diet can increase ghrelin production, fasting can help support normal ghrelin levels.

In addition, data shows that fasting may help increase leptin, the satiety hormone.

7. May Help Promote Normal, Healthy Aging

While more human research is needed, animal studies link fasting with increased longevity, including promoting a healthy lifespan and cellular aging.

How to Fast

Ready to try a fast? Here are some tips to help you accomplish it — with the okay and guidance from your healthcare professional, of course:

1. Decide what type of fast you’re going to do

It can be a good idea to start with intermittent fasting or time-restricted eating, such as 12 hours of fasting. If that feels good after a few days, you can increase the fast to 14 hours and up to 18.

2. Set some goals

What do you want to accomplish by fasting? Lose weight, have more muscle, be healthier, have more energy? Write it down and check in with this goal frequently during your fast.

3. Make a menu and stock the fridge

Before beginning your fast, decide when you’re eating and what you’ll eat then. Knowing this in advance takes the pressure off and will help you prepare. Having a range of healthy foods waiting in the fridge makes fasting a lot easier.

4. Prioritize nutrient density

During eating windows, focus on whole foods rich in protein, fiber and healthy fats to ensure proper nourishment.

5. Hydrate adequately

Unless you’re doing a dry fast, drink plenty of water throughout the day, especially during fasting periods, to avoid dehydration and fatigue.

6. Break each fast mindfully

Avoid sugary or processed foods when breaking your fast. Opt for a small, protein-rich snack like nuts or yogurt, and gradually reintroduce other foods.

7. Monitor progress

Track your weight, energy levels and overall well-being so that you and your healthcare professional can be in lockstep before, during and after your fast.

Common Fasting Questions

Is fasting suitable for women?

Generally speaking, yes, but women tend to be more sensitive to the effects of fasting compared to men. Some women may encounter hormone impacts if they fast for days on end. Therefore, they may benefit from going on a shorter fast, such as a day or two — or intermittent fasting only a few days a week rather than every day, for example.

No fasting should be used to try to achieve unrealistic weight loss goals.

What general precautions should women take when fasting? (Of course, your healthcare professional should be consulted for this.)

Discuss fasting with your healthcare professional before starting, especially if you have any underlying health conditions.

Avoid fasting if you’re pregnant or breastfeeding, due to increased nutritional demands during these stages.

Stop fasting if you experience excessive hunger, fatigue, or dizziness.

Can one exercise while fasting?

Skip intense workouts during fasting. While moderate exercise is typically acceptable if you are already engaged in a regular exercise routine, strenuous activities are best avoided when not fueled.

Generally, you can exercise while fasting if you already are engaged in a regular exercise routine. You might even find that on time-restricted eating, you feel more energetic in the mornings to get your workout in.

As usual, check in with yourself and your healthcare professional. You can always scale back or up depending on how you feel.