What is the Alternate Day Fasting Diet?

Dr. Constance Odom, MD

Medically reviewed by

Dr. Constance Odom, MD

Dr. Constance Odom, MD

About

Constance Tambakis Odom, MD graduated in 1987 with her Doctorate of Medicine from the New York Medical College, and was an Anesthesiologist Resident from 1988 to 1991 at the Brookdale Medical Center PGY II (CA-I)-PGY IV (CA-III). She is Board Certified by the American Board of Anesthesiology since 1998 and American Academy of Anti-Aging Medicine since 2002. Constance Odom, MD is affiliated with the American Medical Association, American Academy of Anti-Aging Medicine, American Society of Anesthesiology, Georgia Society of Anesthesiology, Hellenic Medical Society of New York, North Carolina Society of Anesthesiology, and Society of Ambulatory Anesthesia.

Credentials

Medical Director At:

• Nu Image Medical
• MetroMedispa P.A.

Staff Anesthesiologist at:

• Betsy Johnson Regional Hospital in Dunn, NC
• Onslow Memorial Hospital in Jacksonville, NC
• Duplin General Hospital in Kenansville, NC

Director of Anesthesia Services at:

• Jacksonville Surgery Center in Jacksonville, NC

Written by our editorial team.

Last Edited 1 year ago · 8 min read

Intermittent fasting is a concept that has changed the paradigms of dieting. It encourages zero-calorie consumption and supports the notion of missing complete meals, something that traditional diets detest. But this concept has been proven to work in several circumstances, especially when medical weight-related issues are a looming concern. Intermittent fasting methods include periodic fasting, daily time-restricted feeding, and the popular alternate-day fasting. Alternate Day Fasting, in particular, has been all the rage in recent years as it produces excellent results in short time frames. 

In this piece, we dissect the concept of Alternate Day Fasting, its benefits, and more:

Alternate Day Fasting Broken Down

Alternate Day Fasting, also known as ADF, is a diet that requires users to intentionally abstain from consuming food or calories every alternate day. The concept is quite simple and doesn't require much effort for users to watch the clock like with standard intermittent fasting, which has timing schedules.  

In the Alternate Day Fast, the time frame between consumption and non-consumption is always 24 hours, which translates to a single day. This makes it easy for users to plot their meals and progress. Meals and consumption can be normal on non-fasting days. While the overall diet isn’t difficult to carry out, adherence can be an issue as total abstinence from food is often hard. 

However, the body does become used to non-consumption after a few weeks. For those who can't manage the total elimination of food on certain days, there is a modified version of the Alternate Day Fasting Diet, which is slightly less intense. The modified diet does not require users to fully avoid drinking and eating on fasting days. Instead, a restricted calorie intake is suggested.

Alternate-Day Fasting Vs. Intermittent Fasting

As we mentioned above, ADF falls under the intermittent fasting category. However, these diets are not the same even though they have quite a few similar rules, one of the most common being fasting. Below we briefly explain each diet so you can identify the marked difference between them.

• Intermittent fasting: This diet follows a cyclical eating pattern which means you switch back and forth between eating and fasting periods. The focus of the diet is timing, and there is little to no attention given to what food types are consumed. There are multiple variations of the diet, each with different eating and fasting time frames.

• Alternate Day Fasting: This is a specific version of intermittent fasting. It involves eating normally one day and completely restricting consumption the next. This diet allows individuals to eat preferred food types in desired portions on non-fasting days and does not carry any restrictions. There is only one variation to this diet—the modified version, which we discussed earlier. This version has a minor restriction of max 500 calories on non-fasting days.

These diets should never be followed together as this could result in serious drawbacks rather than benefits. 

Sample Alternate Day Fasting Schedule

The ADF regimen is straightforward and doesn't require pre-planning, meal prep, or extensive buying lists. However, some calorie counting is involved if the modified version is to be followed. As we mentioned before, the modified plan involves introducing eating into fasting days. 

However, consumption must be capped at 500 calories. This can extend to 700 calories if the brunt of the diet is felt too badly. In the Modified Alternate Day Fasting Schedule, the aim is to consume 25-40% of your energy needs on fasting days, while the rest of the non-fasting days have no consumption guidelines or limitations.

Below we look at the schedule for the standard Alternate Day Fasting Diet:

Here we look at the schedule for the modified Alternate Day Fasting Diet:

Whether you are a fasting purist or a modifier, normal consumption—standard, normal meals must be continued on non-fasting days. The calories missed do not need to be replaced or caught up on, so an increase in eating must not be carried over to the non-fasting day. 

Benefits of the Alternate Day Fasting Diet

The benefits of a diet are always confined to losing weight and looking good, but little emphasis is put on their health benefits. Alternate Day Fasting, for example, is more than just a trend or weight loss fad. When we look at the diet from a physiological perspective, the diet is based on fasting.

Fasting is a metabolic state the body enters once the stomach is completely empty (all food and drinks are processed). According to research, ADF is an effective option for promoting weight loss, changing body composition, and reducing cravings/extreme bouts of hunger.

We expand on these benefits below:

• Induce Weight Loss

Weight loss is one of the more publicized benefits of this diet. The diet can help users lose and maintain an ideal weight while preserving more non-fat weight—lean muscle.

- A review study found that overweight or obese adults following an ADF diet for 3 weeks could lose 2.5% of their total body weight. Another study suggested an 8% total body weight loss in 12 weeks.

- A separate research study found that participants who followed the ADF diet for 8 weeks achieved a decreased waist circumference of 7.3 cm.

• Alter body composition

Following the ADF diet can result in a change in body composition. This refers to the body's fat, bone, and muscle percentage. A PubMed study shows that those who follow an ADF diet see a decrease in fat and maintenance of lean muscle mass. This improves overall body composition and BMIs.

• Help reduce the effect of hunger pangs

Extreme bouts of hunger are probably one of the worst things for both the body and mind as it affects rational thinking and physical functionality. Studies show that following the ADF diet can improve feelings of fullness over time. This leaves the body/mind in a better state and reduces the negative effects of hunger. 

Specific Health Benefits that Come with Alternate Day Fasting 

Let's set aside the weight- and body-comp-related results and look at more specific health benefits of the ADF diet. Most often, health benefits linked to diets are few and far between due to the extensive guidelines, restrictions, and adherence difficulty that comes with them. 

But the ADF diet proved to be the difference in this respect as several health benefits accompany the diet. Below list some of the primary health benefits that come with this diet: 

• Improve Diabetes

The ADF diet supports significant fat and weight loss which reverses the symptoms and risk factors of diabetes. Research from a study found that fasting has a positive effect on diabetes and associated conditions. It can also prevent the development of the condition. 

• Eliminate Cardiovascular Risks 

The ADF diet is an effective and sustainable approach to get the body into a target weight range. It helps individuals maintain a healthy weight long-term, directly improving heart health. The CDC (Centers for Disease Control and Prevention) confirms that heart health is greatly improved with weight loss, and risks are drastically lowered. 

The effects of the diet also improve heart health biomarkers such as:

- Reduced blood pressure—A PubMed study shows that fasting can benefit hypertension by reshaping the gut microbiota

- Decreased total cholesterol—According to research, ADF can help simultaneously reduce belly fat and cholesterol levels. 

• Improves Autophagy 

Autophagy is a natural body process that breaks down and recycles old cells. The process helps prevent chronic health conditions and other illnesses. This process is also linked to aging. Clinical evidence suggests ADF boosts autophagy, resulting in:

-Slower aging

-Reduced tumor risk

-Overall better health and immunity

These widespread health benefits are often seen after religiously following the ADF diet schedule for at least a few weeks. 

Is Alternate Day Fasting Safe?

Safety is always a concern when embarking on any diet, so it's only natural for most people to wonder if this diet is safe. After looking at the basics of the diet and studies supporting its efficacy, we concluded that the diet is indeed safe. 

The absence of food, in some sense, can lead some to believe there is a danger of starvation or dehydration, but that's not the case, as non-fasting days allow complete freedom and normal consumption.

The safety and efficacy of the ADF diet were demonstrated in a study involving participants with depression. The results showed:

• Depression and binge eating drastically improved  

• Eating patterns improved, and participants showed a remarkable change in their body image 

• No serious side effects of adversities were noted 

These results show that the diet can be safe and effective for any adult, considering they don't have any experiences with disordered eating behaviors or a diagnosed eating disorder like bulimia and others that thrive on the non-consumption of food. 

Other individuals that are not ideal candidates for this diet are:

• Children

• Those who are pregnant or nursing

• Individuals with clinically low body weight

• People with certain medical conditions or who consume certain medications

We suggest that professional advice is sought if individuals have any underlying health conditions to ensure maximum safety.

The Takeaway

The ADF diet is definitely an effective way to shed excess weight and improve overall health. The basis of the diet is also simple to follow, and there isn't much effort needed to start. The ideal time frames for using the ADF diet can vary from weeks to months, depending on user preference. Although there is a consumption restriction/controlled consumption on alternate days, the diet is very flexible compared to other diet plans introduced into the mainstream recently. This fasting method has also been deemed safe, so in essence, it has all the markings of a successful diet plan.

11 Sources 

Nu Image Medical has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references. 

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https://www.annualreviews.org/doi/full/10.1146/annurev-nutr-071816-064634

https://www.sciencedirect.com/science/article/abs/pii/S089158490600801X?via%3Dihub

https://www.metabolismjournal.com/article/S0026-0495(12)00256-9/fulltext

https://pubmed.ncbi.nlm.nih.gov/26374764/

https://pubmed.ncbi.nlm.nih.gov/33487299/

https://pubmed.ncbi.nlm.nih.gov/34909309/

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https://onlinelibrary.wiley.com/doi/full/10.1002/oby.20353

https://www.tandfonline.com/doi/full/10.4161/auto.6.6.12376

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your physician about the risks and benefits of any treatment. Nu Image Medical may not offer the medications or services mentioned in this article.