Complete Guide to Alternate-Day Fasting

If you are searching for a powerful way to effectively shed some pounds or improve your overall health, alternate-day fasting could be your absolute solution. Experts have found more evidence that doing alternate-day fasting reduces weight loss and lowers the risk factors related to type 2 diabetes and heart disease among average and overweight individuals.

Other fasting types include the 5:2 method, 12-hour fasts, 16-hour fasts, 20-hour fasts, and 24-hour fasts.

Before you jump on starving yourself the next day, it is critically essential that you educate yourself on the benefits and drawbacks of the alternate-day fasting method. Creating awareness of these aspects will help you maximize the results and lower the risks that may lead to potential health complications.

In this article, we will dive into the details of alternate-day fasting, its science-backed benefits and risks, the quality of food you need to consume during the fasting days, and how to start the right and safe way.

What Is Alternate-Day Fasting?

Alternate-day fasting (ADF) is a time-restricted fasting method in which you alternately fast one day, then eat normally the next day, and repeat. In other words, you have a “fasting day” where you eat less to nothing and “feeding days” where you can eat like on any typical day. 

As a popular practice of intermittent fasting (IF), the concept is simply losing weight by fasting every other day. In casual terms, you starve yourself one day, then feast on whatever food you want the next – also called the “every-other-day diet.

How does it work?

On a fasting day, you may consume a small number of calories or none at all. The maximum calorie intake that one can eat on a fasting day is 500 calories, which is approximately one-fourth of an adult’s daily energy requirements. Click here to find out your daily calorie needs based on your age, weight, gender, and physical activity.

On a feeding day, you can go back to your normal eating habits and consume whatever foods and drinks you want.

Some data on alternate-day fasting

Mounting scientific evidence revealed that alternate-day fasting is proven beneficial in weight loss, decreased risk of cardiovascular diseases, and improved blood glucose and cholesterol levels.

Furthermore, one case report claimed that a well-planned intermittent fasting method such as ADF might incredibly help reverse type 2 diabetes. Although it might be too early to conclude that ADF can totally reverse diabetes, scientists are affirmative that IF can potentially provide fantastic health benefits.

How Do You Practice Alternate-Day Fasting?

The ADF method is literally just eating every other day. This is how alternate-day fasting works using the 24-hour alternating fast period: 

  1. Start a 24-hour fast. For example, you would finish your dinner at 8:00 PM on Monday and fast for the next 24 hours. 
  2. You’d break the fast after 24 hours and start another 24 hours as your feeding period. Thus, if you started the fast on Monday at 8:00 PM, your next meal would be on Tuesday at 8 PM. 

Other IF dieters would opt for the 36-hour fasting and 12-hour eating windows. 

How long does it take to get used to alternate-day fasting?

According to a study conducted by Mark Mattson, Ph.D., a neuroscientist from Johns Hopkins Medicine, it can take 2–4 weeks for the body to become accustomed to intermittent fasting. In the early days, the participants experienced hunger or crankiness as their bodies tried to adapt to the new routine. Over time, the participants who made it through the adjustment phase chose to stick with the IF routine as they started feeling better.

Alternate-Day Fasting Results: Before and After

In studies conducted among overweight and obese adults engaged in ADF, it was observed that one could potentially lose 3–8% of their body weight in 2–12 weeks.

See the difference on the first week of following the ADF protocol.

The photo was taken from Strozzo.

Alternate-fay fasting helped him lose 14lb in 30 days.

The photo was taken from Men’s Health.

After 4 weeks of practicing alternate-day fasting and exercising, most ADF dieters observed that they had developed more lean muscles and had less body fat. Moreover, there were also positive improvements in their lipid profiles, insulin sensitivity, and blood pressure.

Alternate-Day Fasting vs. Intermittent Fasting

Intermittent fasting (IF) or intermittent energy restriction is a big term for various eating patterns or meal timing schedules that cycle between fasting and eating over a given period. On the other hand, alternate-day fasting is a type of intermittent fasting where you have an alternating schedule of fasting days and feeding days. 

Other approaches of IF involve time-restricted eating, the 5:2 diet, the eat-stop-eat approach, the Warrior Diet, and spontaneous meal skipping.

Whatever type of intermittent fasting you choose, it can still provide you incredible benefits in weight loss and overall health improvement.

The important point that you should understand is your body’s response to a certain fasting method. In some cases, one type of IF may work for your friends but not for you. Bear in mind that the basal metabolic rate (BMR) and weight loss tendencies differ from person to person.

Thus, it is crucial to identify the best method of intermittent fasting based on your unique individual needs. Consult a health expert and let them assess your health status to design an intermittent fasting diet protocol and give you the best possible outcome.

How Much Weight Can You Lose With ADF?

In scientific research, it was observed that participants had lost an average of 7.7 pounds (3.5kg) after 4 weeks by consuming 35% fewer calories and alternating between a 36-hour fast and a 12-hour eating window.

To maximize your weight loss efforts, combine it with exercise. Research claims that you may lose twice as much weight by combining alternate-day fasting with endurance exercise than just fasting alone. 

The Effects of ADF on Hunger

Any calorie-restricted diet can cause hunger while the body is trying to adapt to the reduced food intake.

During the early times of following the ADF method, intense hunger is expected on fasting days. As a result, some people may find it more difficult to keep up than on a steady reduced-calorie diet.

The Effects of ADF on Your Body

Same as other forms of restricted-calorie diets, ADF can potentially produce similar results in terms of weight loss. 

However, in a 2017 review, it was observed that alternate-day fasting regimens do not demonstrate significant weight reduction compared to standard, continuous calorie-restricted weight loss plans.

Does alternate-day fasting affect metabolism?

Most weight loss methods affect our resting metabolic rate (RMR). This effect is called the starvation mode, also known as adaptive thermogenesis.

When you’re on a severe calorie-restricted diet, your body will typically respond by reducing the number of calories it burns to conserve energy. This effect can hinder weight reduction and make you feel miserable. 

With ADF, it was observed that this weight loss method doesn't seem to cause this drop in metabolic rate.

Based on the results from an 8-week study that compared the effects of standard calorie restriction and ADF, there was a 6% significant decrease of resting metabolic rate under continuous calorie restriction when calculated relative to lean mass, while there was only an insignificant decrease of 1% with ADF. 

Over time, after 24 weeks, participants who were under the calorie restriction had a 4.5% lower resting metabolic rate compared to the beginning. Participants under the ADF method, on the other hand, experienced only a decrease of 1.8%.

The Effects of ADF on Autophagy

The word “auto-” means “itself,” and “-phagy” means “eat.” Basically, autophagy is referred to as the “self-eating” process. 

In that sense, autophagy is the body’s way of clearing unwanted substances from the cells by recycling unused, damaged, and potentially harmful cell components.

Autophagy is known for its key role in preventing non-communicable diseases such as cancer, neurodegeneration, heart disease, and infections. It’s also linked with the aging process.

Alternate-Day Fasting Schedule

The alternate-day fasting calendar is easy to follow. Just think of the days as an eat-fast-eat-fast diet pattern. This equates to a repetitive cycle of 24 hours of fasting and 24 hours of eating. Here’s an example of a suggested ADF schedule:

Sunday: Healthy full meal day 

Monday: Fast day (or eat less than 500 calories)

Tuesday: Healthy full meal day

Wednesday: Fast day (or eat less than 500 calories)

Thursday: Healthy full meal day

Friday: Fast day (or eat less than 500 calories)

Saturday: Healthy full meal day

It’s fine to modify the schedule as long as you stick to the solid idea of ADF. The challenges, in the beginning, will be tough, especially if you immediately decide to start the fast without eating. Thus, you might want to start with eating a few calories on your fasting days. Take it slowly.

The Benefits of Fasting Every Other Day

ADF is a powerful weight loss tool that is easy to follow. There are several benefits that this fasting pattern can offer to your health. These include:

1. Supported weight loss

According to the World Health Organization (WHO), obesity is now a global epidemic. It is identified as one of the major risk factors behind common morbidities such as diabetes, hypertension, and heart problems. 

How can alternate-day fasting help you with your weight loss struggles? There are several studies that support this claim. 

In a 2013 study published in Nutrition Journal, participants lost nearly 8lb of fat mass following the ADF method for 12 weeks. 

Moreover, another study claimed that people ages 50–59 were able to achieve greater weight loss results with ADF compared to people of other age groups.

To maximize your weight loss efforts, you can also consider combining ADF with endurance exercise. It is supported in a 2013 study that the combination of endurance exercise and ADF can burn at least twice as much fat compared to following an individual approach.

2. Improved heart health

Heart disease, also referred to as cardiovascular disease, is the worldwide leading cause of death. The WHO 2016 statistics revealed that heart-related diseases accounted for more than one-third of deaths globally. 

Combined with a healthy lifestyle, alternate-day fasting can lower your risk of heart diseases. It can:

3. Controlled blood sugar levels

High blood sugar levels occur when the body’s pancreas fails to produce enough insulin or when there is insulin resistance – the inability of the body to utilize insulin. Persistent increase of blood sugar to abnormal levels can eventually lead to diabetes.

In a pilot study, short-term application of alternate-day fasting or other forms of IF can help reduce blood glucose levels. ADF works by reducing the blood levels of insulin to increase your body’s insulin sensitivity.

4. Stimulated autophagy

Long-term and short-term ADF has the potential to stimulate autophagy. In animal studies, it was found that it can reduce tumor development,slow down the aging process, and improve longevity.

5. Promoted longevity

With the calorie restriction involved in ADF, it was found that it can significantly promote longevity based on animal studies.

In many studies, animals that received a calorie-restricted diet supplied with all necessary nutrients survived longer compared to their counterparts that received more calories. 

In fact, calorie-restricted animals have significantly lower risks of many age-related disorders, including cancer.

With these studies, it should be noted that you should carefully interpret the data as the results from the animal studies do not accurately translate to humans as well.

What to Eat and Drink on Fasting Days?

On your fasting days, you may consume up to 500 calories only. Thus, you will need to plan what you’re going to eat and drink during the fast days

Ideally, consume foods that are high in protein and low in calories. High-protein foods include lean meat and eggs. Low-calorie foods include vegetables, fruits, warm soups, and Greek yogurt. As for your drinks, you can take unsweetened and creamless tea or coffee only. 

You have a choice if you prefer to eat a “big” meal once a day or 2–3 small meals throughout the day. Just make sure not to consume more than 500 calories.

Can you drink water during alternate-day fasting?

Whatever diet you are following, you should never take water out of your day, even if you’re on a zero-calorie day. 

Make sure to drink plenty of water – up to 8 glasses of water a day. Water intake is critical to prevent dehydration and hunger pangs.

Alternate-Day Fasting Safety and Risks

Alternate-day fasting is generally safe for most people, especially when done short term. The long-term negative health effects of ADF have not been well documented yet.

Note that during the early days of your ADF journey, you may experience the following signs:

  • Constipation
  • Dizziness
  • General weakness
  • Bad breath
  • Sleep problems
  • Disturbed menstrual cycles in women
  • Low mood, anxiety, and depressive symptoms in normal-weight individuals

Fortunately, these are mild problems, and you can easily overcome them over time as your body adapts to the new eating habit.

You should keep in mind that alternate-day fasting is not the best method for IF newbies. Why? ADF is an extreme form of intermittent fasting, and there is a tendency that you may discontinue it for longer durations.

It is essential to note that just like any other fasting method, it may cause problems for people who have chronic conditions such as hypertension and diabetes – especially under medication. 

As a general rule, make sure to seek the advice of a medical professional before you start any type of fasting method. 

Pregnant and breastfeeding women, children, and underweight individuals should also get approval from their doctor before starting the fast. 

Concerns have been raised about the possible negative effects of ADF on people who have pre-existing eating disorders. However, a study suggests that ADF may actually be beneficial to people with eating disorders. Thus, such adverse effects are rare and are unlikely to cause any long-term effects on health. 

To help you get started with your intermittent fasting journey, DoFasting, a fasting app, can help you achieve desirable results. The app features include: 

  • Daily motivation boosts
  • Challenge mode
  • Meal recommendations
  • Progress tracker and calendar
  • Effective training routines
  • Tips and guidance


Alternate-day fasting is an effective and safe weight loss tool, and it can generally improve your overall health by reducing the risk of heart disease and improving glucose metabolism.

Seek the advice of your doctor before you start following the ADF method – especially for pregnant or lactating women, underweight individuals, people under certain medications, and children. 

Let the experts design your specific intermittent fasting diet plans to get optimal ADF results.

Start your journey today! 


  • Can you drink water during alternate-day fasting?

Yes, it is entirely safe to drink water while you’re doing intermittent fasting. It is only solid foods that will break your fast and allow your body to re-enter the fed state. It will last for a few hours to break down and digest food. 

There’s nothing to worry about as water has no calories and does not affect your blood sugar or insulin levels. In fact, you do need to drink water to prevent dehydration. 

  • Can you chew gum while fasting?

A piece of sweetener like gum will only have a small effect to stimulate insulin production. Technically, it does break the fast, but it is not too much of a problem to worry about. 

  • How much weight can I lose if I fast for 3 days?

Based on the 3-day diet, dieters were able to lose up to 10 pounds in three days. Since this method requires a very low-calorie intake, it makes it possible for one to lose weight.

However, it should be noted that weight loss is individual for everyone as there are many factors without your diet, such as water weight, physical activity, genetics, etc. 


See how DoFasting will improve your life

Find out what works for you with this 60-sec quiz approved by our experts and get your personal revolutionary fasting assistant.

Start the quiz

We use cookies to improve our services and visitor experience. Your preferences may be changed or withdrawn at any time. For more information, please see our Privacy Policy