Alternate Day Fasting (ADF) Guide

Alternate Day Fasting (ADF)

Alternate Day Fasting, also known as ADF, is a popular fasting schedule. And for good reason! It works, and it works well. 

Let’s look at ADF’s, the benefits, and how to do them.

ADF – First things first

For those who are new to fasting, or maybe just need a refresher, let’s briefly go over what fasting is and why it works for health and weight loss.

Fasting just means you don’t eat anything, for whatever amount of time you’ve decided to fast. 

You drink water, tea, or coffee, and take electrolytes during the fast. 

Fasting works because it lowers insulin, the fat storage hormone, and switches your body over to the fat burning system. 

That’s fasting in a nutshell. Now let’s look at ADF. 

How does the ADF schedule work?

Alternate Day Fasting is super simple. You eat one day, and your fast starts after your last meal. 

Then you fast all day the next day. 

The following day you can eat again. And you keep this cycle up – fast one day, eat the next. 

Depending on what time you close your eating window, and what time you open it up the next eating day, most people get anywhere from 36 to 42 hours of fasting per ADF cycle.

How easy is that?

Pros of ADF

What makes ADF so popular?

Weight loss 

With ADF, you are regularly lowering insulin and going into fat burning mode, especially if you’re following a Low Carb or Keto lifestyle on your eating days. 

Most people who do ADF report that the weight comes off quickly. 


Autophagy, our built-in recycling system ramps up during fasting, and it’s thought to peak at around 36-42 hours.

So with ADF’s you’re repeatedly hitting that sweet spot for autophagy and getting lots of healing.

You can read more about autophagy in our previous article. 


As already mentioned, ADF is an easy schedule to follow. 

Fast one day, feast the next.

Not as challenging as Extended Fasting 

Knowing you can eat the next day makes fasting days easier. Most people can get through one day of fasting. 

I personally find that the hunger isn’t so bad. I’m not hungry till around lunch time on the fast day, and I have some tea or sparkling water and the hunger goes away.

I get hungry again later in the day, but again, it’s not so bad. 

Even on the eating day, I’m not hungry when I wake up and usually wait till lunch time to eat. 

Cons of ADF

As with anything else, Alternate Day Fasting is not perfect. 

Challenging for newbies 

If you’re new to fasting, ADF can be hard at first. 

I suggest building up to it. 

Start with something like 18/6, then 19/5, and then OMAD. 

Once you’re comfortable with OMAD, then try some ADF. 

Read more about various Intermittent Fasting protocols in our IF guide

Overeating on eating days 

Especially at first, there can be a tendency to overdo it when you get to eat. 

It’s like this idea that we have to eat more than we need because we know we’ll be fasting again the next day. 

I find that this urge to overeat settles down after a week or so of following this schedule.


If you’re on daily medications that have to be taken with food, you won’t be able to have a full day of fasting. 

Always speak to your doctor if you have any questions or concerns.

Social situations

It can be tricky when situations that revolve around food come up on a fasting day. 

Life happens, and you can’t always plan for it. Maybe a friend pops up and wants to have lunch on a fasting day, or the boss schedules a meeting with lots of snacks. 

The good thing is that fasting is flexible, you can always switch things up. 

Just don’t get into a habit of going off schedule. You don’t have to be perfect, but you do need to be consistent. 

What can I eat on eating days? Do I have to do Keto?

One of the really cool things about ADF is that you can eat whatever you want on feast days. 

Now, let me clarify that: this does not mean that you should eat junk food (stuff that has no nutritional value).

What it means is that you should aim for nutrition and focus on whole foods, but have what you want. You do not have to do Keto, although the weight loss might come more quickly if you do. 

Think of eating days as refueling days. You want to get lots of nutrition and fuel your body up for the next fast day. 

All that being said, it’s okay to have a special treat on eating days as long as you don’t go crazy with it. 

Bonus tip for eating days: DO NOT restrict calories if you’re still hungry! Always eat till satisfied. 

You can have as many meals as you need on eating days, but try to have your last meal before dark. Food eaten at night tends to take longer to burn through, so you won’t have as much time in fat burning mode. 

ADF might be the perfect schedule for you!

Give Alternate Day Fasting a try and see how you do with it. 

Especially if you’ve tried other fasting schedules and they didn’t work for you. This might be the one!

Author: Roo Black

Roo Black

Roo is a fasting coach with over 5 years of experience. She leads the admin team of the Official Fasting for Weight Loss Facebook group – one of the largest fasting communities on social media with over 125,000 members. We highly recommend this group for anyone who is looking for fasting advice or coaching.

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