Alternate Day Fasting: Know How It May Help With Weight Loss

Medically reviewed by G. Liakeas, MD FACT CHECKED

Alternate Day Fasting is an example of this type of dieting where you fast for one day and then eat regularly the next. You could choose any time interval that suits your lifestyle.

If you have time to exercise in the morning before breakfast & need some energy in the evening after work, you might choose to fast every other day from 6 pm until 12 pm.

The health benefits are the same whatever you choose as long as it is an overall calorie restriction. There do not appear to be any disadvantages if you want to try it for yourself.

However, those who have any health issues should discuss the program with their physician before attempting it.

Fasting involves short-term calorie restriction on day 1 followed by ad libitum (eating of regular portion sizes) on day 2.

Fasting could include a complete fast or partial fast (consuming less than 25% of estimated daily energy needs).

Alternate Day Fasting, where one-day fasts and other days are included in the total energy intake, also has been shown to increase insulin sensitivity and improve markers of metabolic syndrome.

All About Alternate Day Fasting

The alternate day fasting diet involves eating regularly for only 24 hours of the week, then fasting for the next 24 hours.

This is usually achieved by reducing calorie consumption either by not eating, or not consuming any food after a certain time in the evening.

The Fast Day or Zero Day is usually non-consecutive, so you could have weekends off. You may be able to exercise at low intensity on Fast Days, but high-intensity exercise is almost impossible.

A complete fast for one day means you may not consume any calories at all. This is difficult to do and is not recommended. A partial fast means you simply eat less than your usual daily intake.

It is estimated that a typical fast could reduce calorie intake by 20-30%. This could be achieved by eating less food or reducing portions, or by fasting for a longer period.

Most people will choose to use a combination of these methods to achieve the desired effect.

Insights On Alternative Fasting

Alternate day fasting is the practice of eating fewer calories on certain days, and it may help you lose weight. It’s also known as intermittent fasting (IF) and time-restricted feeding (TRF).

Alternate day fasting could be done by restricting your food intake to 500–600 calories per day on two consecutive days each week, fasting for 24 hours once a week, or alternating one or two days of full meals with one or two days without anything to eat.

According to a study on alternate days, fasting could have many positive health benefits in humans. You might shed as much as 4-5 pounds per month while eating this way! But there are some potential pitfalls too.

Before you try alternate day fasting, it’s best to seek a doctor’s recommendation and make sure you have read the risks and benefits.

The benefits are that your body goes into starvation mode on a fast day; therefore, it has to burn fat to maintain healthy blood glucose levels. But this could be dangerous if you aren’t careful.

Over time your body may become accustomed to eating less food on fast days. You may experience slower metabolism or a loss of muscle mass as you get older.

It could also be difficult to determine how many calories you need each day without tracking them through diet or counting calories with a calorie tracking app.

The Three-Day Diet

The three-day diet is one of the most common forms of alternate-day fasting. Follow this intermittent fasting plan for three consecutive days each week:

On day one, eat normally, but no later than 6 pm. On day two, don’t eat anything after 8 am and consume only a cup (equivalent to roughly 500 calories) of vegetables between noon and 6 pm.

On day three, eat normally again. Although this may seem like a long time to not have any food in your system on a fast day, it’s pretty easy once you get used to it.

Health Benefits Of Alternate Day Fasting

Alternate day fasting, or ADF, is an intermittent fasting protocol where you could consume your normal amount of calories on one day and restrict it to 275-500 calories on the other day.

Following is the list of health benefits of alternate day fasting. Read Ahead!

  • It reduces body fat mass, particularly in the abdominal region
  • It lowers Total Cholesterol (TCHO) and LDL Cholesterol levels
  • It improves insulin sensitivity and insulin sensitivity markers (HOMA-IR)
  • The Alternate Day Fasting protocol decreases pro-inflammatory cytokine production by macrophages, immune system cells that play an important role in the progression of various chronic illnesses
  • It increases anti-inflammatory cytokines such as IL-10 and TGFbeta1
  • It reduces blood glucose levels and blood insulin levels 8. It improves glucose tolerance
  • It decreases blood pressure
  • It improves heart health markers and reduces arterial stiffness
  • It improves markers of longevity and well-being
  • It has the potential to be a treatment for cancer
  • There are no adverse effects in healthy adults (except maybe insomnia)
  • Ingestion of L-Leucine with every meal may increase protein synthesis and suppress muscle breakdown in the body during fasting days
  • Alternate Day Fasting has been demonstrated to improve blood lipid levels beyond that of weight-loss dieting alone 17
  • Alternate Day Fasting may decrease glucose tolerance, insulin resistance, and insulin sensitivity independent from caloric restriction
  • Improved Cognitive Function. Not only is it easier to concentrate during fasting periods, but low blood sugar has been shown to reduce the risk for Alzheimer’s disease and other types of dementia

Alternate day fasting has many benefits, the most promising of which include weight loss, increased longevity, improved mood health, and reduced risk for chronic diseases.

The best part is that it’s probably not as hard as you think to try out this health hack.

When it comes to figuring out how long you should fast per day, we recommend starting with two 48-hour periods that alternate between eating and fasting.

This will allow you to gauge how you feel during the fasting period and prevent your body from getting used to breaking your fast.

How Well Does Alternative Fasting Help In Weight Loss?

Fasting is a centuries-old, life-sustaining practice that people around the world engage in to deepen their spiritual and religious beliefs, heal from physical illness, and reform their lifestyles.

What many people don’t know is that fasting could also be used as a form of dieting to maintain a healthy weight.

The only catch is that alternative fasting is a process and so it takes a lot of preparation on the part of the individual to do this; most people in our society are not willing to follow through with the necessary changes they need to make in their life.

This means that alternative fasting has not really been thoroughly tested, and so there is no hard scientific data to speak of.

It would be foolhardy for anyone going into alternative fasting without some background knowledge about how their body processes food and what hormones are at work as well as what types of calories their body uses.

You must also keep in mind that you have a body that is used to having your normal routine. You will have to adjust to this new way of living, and it is not for the faint of heart.

ADF Works Wonder For Those Who Do It Well

Getting back to the point of what alternative fasting does for those who give it a try, the list of benefits that people who follow an intermittent fast get would be endless.

They include a deeper understanding of how their body processes food and how healthy energy nutrients need to be processed by them.

Incorporation of rest into their daily life so they could do more than accomplish only one thing at a time instead of filling up their days with a bunch of busy work.

A chance to break free from food cravings that have kept them down because they could not reach their ideal weight and level of health. Faster metabolism so they could lose weight faster as well as keep it off once they reach their ideal weight.

Interaction with other like-minded people who are working in the same manner as them or want to start.Improved confidence about themselves and the goals that they want to achieve for better physical health.

Increased energy levels so that their body does not feel sluggish after a meal but is ready to move on with their day once again. Faster recovery time after an injury due to overexertion because of overweight problems.


As telomeres shorten with age, alternative fasting may be a most helpful way of maintaining or possibly even lengthening them.

ADF has a reciprocal effect on rejuvenating the immune system and protecting its DNA from damage.

It’s not just fasting that serves as an immune booster; restricting calories in general also helps keep your body in shape as it works to maintain weight loss while generating protective hormones that promote healthy aging while fighting disease.