Alternate Day Fasting – Fast Days

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The final piece of the puzzle, everything you need to complete your ADF plan.

I’ll open by saying there is no ONE way to do this, there is a toolbox of methods you can employ to either make the fast easier or more potent. Here’s the rundown:

How long do I fast?

Although in theory an “alternate day fast” could simply be avoiding calories for a specified amount of time, every other day, In my opinion to be a legitimate ADF set-up you need to be fasting for 24-36 hours. You could realistically fast for 16, 18, 20, 22 hours, or any amount in between, every other day but I’m not willing to say that such a method boasts the same results as the ADF schedules we suggest. 

As a general rule of thumb, you receive bodybuilding and physique enhancing benefits with a 24 fast. At this point free fatty acid release reaches its peak, insulin reaches its trough and IGF-1 levels start to decline, this will be covered in greater detail in another article. With this in mind, at the 24 hour mark it is a good idea that those with an aesthetic or performance goal in mind to end the fast (more on this later). If you want to push things further, Alex from ForeverAlpha has written this piece on 72hr fasts.

If you’re seeking neuro and cellular protective benefits you could take the fast to 36 hours. You could go for 36 hours with aesthetic/performance goals in mind but I’m not convinced that you would receive much additional benefit as far as these goals are concerned – you may even just run yourself into the ground, be mindful that completely avoiding calories for 36 hours on a regular basis while training hard is an extremely stressful and draining way of life.

How do I set up a schedule?

First, decide what you want to achieve with ADF, (health enhancement or physique/performance improvement), here I will assume the latter.

So, you know that you need periods of 24 hours where you abstain from calorie consumption. Obviously we want to reach a point where this is every other day, hence the title, however jumping in at the deep end may not be the most efficient path to take.

Fasting for 24 hour periods is a stress and a shock to the body so we recommend taking baby steps and introducing it slowly.

I suggest running the fast from one evening (stop eating at 9pm on Monday) until the evening of the following evening (resume eating on the Tuesday at 9pm). Although you could realistically run the fast between any two arbitrary times that are 24 hours apart.

I would begin with one or two of these per week, this should be your baseline and you would still get good results from fasting twice per week.

From here there are two options for progression. You could continue to add fasts in a manner that meant you eventually simply fasted for ~24 hours every other day. This is a great method and really the optimal way to perform ADF.

Another legitimate set up would be the following:

Monday – 24 hour fast

Tuesday – feed

Wednesday – 24 hour fast

Thursday – feed

Friday – 24 hour fast

Saturday – feed

Sunday – 18-20 hour fast

Monday – 24 hour fast 


This way allows you to have a rigid structure to work around each week and makes social arrangements easier to plan – you also get to eat on both days at the weekend. The cost for this addendum is 4-6 hours lost fasting per week, a small price to pay if increased compliance and a more enjoyable life is the result.

Notice, I specify around 24 hours, its not a concrete number, some days you will prefer to fast longer, others slightly shorter (no shorter than 23 hours though, on an infrequent basis), err on the side of too long rather than too little. A good way to go would be to simply break the fast an hour before bed, assuming you’ve completed 24 hours, this way it wont become an all consuming time that you work around.

What can I and what can’t I consume? 

The simplest answer here would be water (lots), green tea, black coffee and nothing else. Keep your calorie intake at zero and show insulin who’s boss.  Arguably this method works the best in terms of reaping the results from the fast.

However, optimal theory isn’t always an optimal real life application, we want to get as close to this as possible while still allowing us to go about our daily business – enhance it even. Feel free to try this once you’re used to fasting, if you can manage it, i’d recommend that this becomes your regular practice – only look to make changes if things become problematic

Encouraged additions 

  • Magnesium: this will help you tolerate the stress a bit better, as I’ve mentioned, fasting is a stressful activity so its useful to try and manage it as best as possible.
  • Leucine, Glutamine and Electrolyte salts: a combination of 3g, 10g and 1g respectively with added lime and lemon slices in around 2L of water makes a great workout drink, Its past the scope of this article but dehydration is inherently catabolic and hydration is inherently anabolic, this amino mix will encourage cellular hydration. Glutamine also serves to protect the stomach lining from increased gastric acidity during the fast.
  • The Pump by Myprotein is a caffeine free preworkout amino mix that we rate for fasted training.
  • ZMA + sleep supplements: Fast days will cause elevated cortisol and noradrenaline levels in the body, so you’ll feel very awake into the evening, as a result, getting to sleep may be a little challenging occasionally. Its worth investing in some ZMA and a quality sleep supplement to help you dose off.
  • A small evening meal, as I mentioned, assuming you’re goals aren’t life extension and disease prevention its a sensible idea to have a small meal before going to sleep, it keeps the extreme stress (that occurs between 24-36 hours) under control and keeps IGF-1 from dropping too much.

There are some very specific guidelines with this:

  • it must <20% of your total calorie requirement, there are some studies suggesting that all of the benefits of fasting may still be experienced with a calorie intake this low, 300-400kcal would be a safe start.
  • Protein dominant, with some fats: you should look to get at least 30g of protein in this meal, and some fats are acceptable, keep carbs to a bare minimum (chicken, beef, salmon or white fish are good options)
  • Include green vegetables: kale, broccoli,
  • Add a fibre supplement to lower the glycemic index and load of the meal and amplify satiety, psyllium husk is a good option.
  • Include a multi-vitamin, a few grams of fish oil and some vitamin D, this ensures your bases are covered to a large extent.
  • Eat at the 24 hour mark or shortly after, not before.

Other additions 

You can consume small amounts of semi-skimmed milk in coffee, this will have negligable effects on insulin as long as it is used sparingly (1-2 tsps in a cup every 3-4 hours), . Some fats are acceptable very sparingly, any fat consumption will interrupt the fasted state so its the sort of thing that you should keep for a last resort.

Raw vegetables are an option, things like broccoli or unpeeled cucumber – volume devoid of calories, some fibre and good mineral/vitamin content. Again, , not an excuse to nibble all day. Use sparingly.

A fat burner may be an option for those with rapid fat-loss as a goal but I’d recommend it only for those who are used to fasting and have been doing it a while.

How should I train? 

Keep the heavy training for feed days and follow the eating recommendations, you’ll be in a very anabolic, rebounded state and training heavy with high volume on these days will take advantage of this.

Cardio is a great addition to fast days, try to perform it in the evening when fatty acid blood levels are at their highest (you’ll burn more fat in the evening) and keep it relaxed. Incline walking on a treadmill at a pace that would allow you to hold a brief conversation. Make sure you consume plenty of water here.

You can also add some light weight training on fast days if you choose. A good set-up would be to perform some light isolation work for the muscle groups that you trained the previous day. You could also use the fast days to accumulate an amount of total weekly volume for a weak body-part.

A good way to look at a fast day is an opportunity to take care of yourself, a bit of spring cleaning. You’re gastic system is getting a rest and you’re body uses the fast as an opportunity to cleanse the system of toxins accumulated from bad food choices and environmental stress. So, why not use the time to foam roll, stretch, do some pre-hab, even take up yoga or meditation, you’ll wake up the next day feeling much better.

Dominate life 

Try not to look at a fast day as unpleasant, focus on the experience. You’ll start to realise that you actually don’t need the food vices that you normally rely on and think you require to stay focussed. Look at the day as an opportunity to get stuff done, get out the house, away from food preparation areas and gluttonous house-mates and be conscious of the fact that at each passing second your making a better decision than almost everyone in the room, literally experiencing constant improvement. You’ll likely feel awake, alert and, , euphoric. So, go out and dominate life.

33 replies on “Alternate Day Fasting – Fast Days”

Leucine, Glutamine and Electrolyte salts: a combination of 3g, 10g and 1g respectively with added lime and lemon slices in around 2L of water

sounds either amazing or awful – where do you get the electrolyte salts/are there any that you recommend or don’t? I really want to try it.

I am wondering about doing a high intensity workout on fasting days. I understand how important it is to get sufficient protein after a workout. Does this mean taht I shoudln’t workout on a fasting day, since eating protein would be breaking the fast?

High intensity cardio should be avoided on fast days, but you can do the forms of training outlined in the article without a problem. 1 scoop of whey isolate is optional

How would you go about adding in a 36-40 hour fast? Maby fasting on Saturday and having a leangains style rest day on Sunday? Do you think that would counteract the weekly deficit?

Actually, whats wrong with doing 36 hours every other day and just having a huge feeding window post workout?

Hey Chris – that’s what the three of us did for about 12 weeks, 36 hour fast, 12 hour eating window. Worked well and allows a lot more flexibility with food choices, but if you just eat junk permanently you won’t lose fat as rapidly

I don’t eat much junk food, I just love eating massive ammounts of things like meat, veggies and potatoes. But its really nice to know if im with my buddies and they want to make a pizza, or if im with my mom and she wants to make panini sandwiches I don’t have to stress about it screwing up my “carb refeed.”

Im gonna give this a try, it might turn into a 40/8 split because I am no fan of breakfast and I love fasted training. I might have to resort to loading up on mesa sunrise and whey post workout.

Im really interested in gymnastics, I did some basic stuff like wall hand stands, L-Sits, Planches and front levers while I was between gyms. Do you have any suggestions on where to start and how to program it alongside strength training?


Ps- You guys need to advertise your site more, its by far the most no-BS fitness site Ive come across.


During your 36 hour fast/8 hour feeding experiment, how much fat did you lose? Did you overcompensate on cals during the feed to stave off muscle loss? Thanks.


Hi Saleen. I certainly did overcompensate: 6000kcal on feeding days. This helped keep me lean while gaining strength but calories were too high for me to lose significant amounts of fat.

If I were to do ADF again I would keep weekly calories in a slight deficit to lose more fat.

f.a.o. Ben
Dear Ben
You were kind enough to give me advice via email some weeks ago. I (and my wife) have pursued a regime of fasting for 24 hours for 2 days per week for the last 8 weeks. Our hope was that we would lose weight (up to 4kg each). Both of us are now about the same weight as we were when we started, so something is not working as we expected. Could be lots of reasons. However, on the positive side, we have not GAINED much weight, I feel slightly better all round, my blood presure is quite stable and in the right range for my age, and we both have a better understanding ouf our dietary habits. We probably won’t continue the fasting, since the fast days have become something of a chore in the absence of even a slight weight loss (i.e. what’s the point?). Just thought I’d let you know; I’m not expecting a response. Tnanks for all your help.
Ron Havenhand

Sorry to hear that, Ron. I’d be interested to know why. I hope you achieve your goals anyway, even if you choose not to use ADF. Have you tried the Propane Protocol?

Harrison said:

Leucine, Glutamine and Electrolyte salts: a combination of 3g, 10g and 1g respectively with added lime and lemon slices in around 2L of water

sounds either amazing or awful – where do you get the electrolyte salts/are there any that you recommend or don’t? I really want to try it. not strictly an electrolyte supplement but we sometimes use this to avoid hangovers – works about 80% of the time

Just came across your excellent blog on ADF which I have been on about 5 weeks and have lost 14 lbs thus far. Have another 20-25 to go to fully recomp (started @ 30% bf and need to cut that by at least 50%). Love your suggestions. It’s a lot tougher to do lean out @ 54 as compared to 24 without chemical assistance.

I previously tried IF 16/8 to 20/4 which only worked minimally because I was still eating a surplus of calories during my refeed window. I have kept my same diet (modified paleo/keto), but at a caloric deficit, and am counting calories daily. The only thing I am finding a bit difficult is the hunger on the fasting days (which aren’t really fasting but just reduced calories of 25% of feed days). Strength and stamina thus far does not seem to have been affected.

My biggest concern is losing lean mass when dropping this much weight. Here is my body comp analysis done over the course of over 4 years (the methods used: BodPod; DEXA which are both considered as accurate as UWW):

Let me know your thoughts.

“It’s a lot harder to loser weight at 54” – 14lbs in 5 weeks isn’t too shabby Tim!

Honestly I’d say if the hunger is unsustainably strong on your fast days, it could be that ADF isn’t for you. It’s good you recognised the issues with your previous IF experiences and eating a calorie surplus, but ultimately that’s the only true guarantee of weight loss. The evidence so far suggests you haven’t lost any strength, but if you’re concerned about lean mass loss, it may do you better psychologically to follow a regular, higher meal frequency approach. There is much lower propensity for LBM loss at 30% bodyfat provided you’re training with sufficient frequency/intensity.

Hope that helps,

Some would say, why do alternate day fasting at all and just eat your average of the two days each day? I mean, do the studies really show increased immobilzation of fat and lipolysis on CR-restricted or fasting days as opposed to refeed days?

In combination with calorie restriction, what is considered the most effective macro configuration for rapid fat loss? Keto vs high protein/low fat/low carb?

I had a friend shred up drastically on a high protein (65% protein, 17.5% carb and 17.5% fat configuration) and drink 8oz water every hour for 16h = 1 gallon for 15 weeks.

So, it’s not really TRUE alternate day fasting, as it is “warrior style’ feast one day, then normal eating the next? In another of your posts you mentioned total fast days, followed by eat normal/big days. what would you say are the benefits are of true alternate day fasting paired with weight training on feed days? Any better or worse than this method?

Oh sorry about that. I didnt mean feasting as in a large meal, just the warrior ‘style’ of a meal in the evening one day, followed by normal eating the next.. is that the correct protocol?
I had always assumed alternate day fasting to mean total no food days, followed by normal eat days. what would you say the diff/benefits are between that approach and the one you outline here, assuming my main goals are physique based?

Two questions:
1. The coffee drinks on the fasting days are obligatory? I don’t like coffee.
2. “High intensity cardio should be avoided on fast days”. 45 minutes of indoor cycling at 65% – 75% heart rate is low-medium-high?

Hi Juan,

1) That’s fine, it’s optional. Green tea would do nicely
2) That’s medium – what’s your purpose of the cardio?

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