Fasting Supplements | The Complete Guide

Fasting Supplements

This content has been Fact-Checked by a Certified Nutritionist in our Publishing Team. Learn more here. Always consult a medical professional before commencing any diet.

When it comes to fasting supplements; be it intermittent fasting or prolonged, it is important to know what supplements you can take without breaking your fast.

Although not everyone agrees on everything, there is one point of consensus, consuming anything that contains calories while fasting is a no-no.

So, read on if you want a complete guide to supplements to take (or to avoid) while fasting.

Can I Take Supplements While Fasting?

Well, the short answer is yes. But taking supplements while fasting can be a little more complicated.

Purists will tell you not to supplement during a fast for the reason that any sort of nutritional compound will theoretically kick you out of a fasting state.

In essence, they are correct, but only if the supplement contains more than 20 calories or fools your body into raising insulin.

Short and Prolonged Fasting Supplements

Fasting Supplements - Food
You can get all your micronutrients from food.

Is it really necessary to take dietary supplements during a short fast? Well, not really. Your body does need a certain amount of vitamins and minerals to function optimally. It is, however, completely capable of getting enough to survive from the food you eat.

Some health professionals even argue that

if your body keeps getting an extra supply of nutrients above the food that you’re consuming, its ability to make use of any stored vitamins and minerals is reduced.

Yes, your body actually stores all these goodies in your bones, fat tissue and other locations, so you don’t have to supplement daily.

Actually, depriving your body of some nutrients will actually make you stronger according to this research – through a process called hormesis.

What about longer fasts?

When you are fasting for longer than two days, your body will be breaking down all the dead cells and waste inside your body during a process called autophagy.

During this process, your body will release the stored micronutrients. This means your stores will get depleted easier than during a short fast and, thus, supplementation is a good idea.

Supplement Confusion

To understand the supplement divide in the fasting world, let’s take Branch Chain Amino Acids (BCAAs) as an example.

Team A will say since BCAAs form to combine protein, you are in essence not fasting if you drink it because you are consuming a tiny amount of protein that will raise your insulin levels. Team B, however, will loudly proclaim nonsense, while holding the supplement in hand.

The fact of the matter is, the diet/ weight-loss industry is a multi-million-dollar industry, and people will try to monetize everything.

They are looking for ways to make money from it. BCAAs and coffee are two of the ways they are trying to make a quick buck from something that costs nothing.

A Closer Look at BCAAs

So, let’s look at the truth behind BCAAs and fasting.

The label on the bottle will typically read that it contains 0 calories. However, that is not true; it might not contain protein, carbs, and fats, but that does not mean it is calorie-free.

A calorie is something that can be metabolized into energy and BCAAs when consumed have been shown to do just that.

If you’re still not convinced that BCAAs will break your fast, let’s look at leucine on its own which is one of the BCAAs. Studies have shown that it pushes your insulin up majorly as a way to move through the body and do its job.

Now, one of the big reasons people take BCAAs when fasting is because they are afraid of losing muscle.

Firstly, if you consume enough protein in your diet assuming you are doing OMAD, you will have more than enough amino acids in your body. Secondly, the Human Growth Hormone that is produced while fasting will take care of your muscles. As you can see, supplementation with BCAAs is a waste.

With all these conflicting studies how do you know who is right? Since you will find information to back up both sides, go with what you feel comfortable with and believe is best.

But not all supplements are such fence-sitters as BCAAs.

Fasting Supplement Options

Fasting Supplements - BCAAs
If you want to drink BCAAs, do it during exercise.


Wait, but up there it just said that BCAAs aren’t allowed! See, this is where drinking supplements while fasting gets confusing.
If you exercise in a fasting state, you can add BCAAs to your drinking water while training. It is an excellent source of energy for your muscles. And the benefits of sipping on it while you are working out far outweigh any negatives.

Avoid using BCAAs if you are pregnant, breastfeeding and if you suffer from branched-chain ketoaciduria.

Other Amino Acids

This includes beta-alanine, betaine, D-aspartic acid, L-carnitine and creatine (although not technically an amino acid).

Creatine is in a grey area though. Some studies have shown that creatine monohydrate (unflavoured) has the potential to raise your insulin even though it does not contain any calories. These studies were done on rats, while another study in humans showed that 5 g of creatine monohydrate did not affect insulin secretion.


If you’ve been in the fasting game for a while, you will know that low sodium and potassium levels lead to low energy levels, muscle cramps and dizziness. Electrolytes help maintain high energy levels and your body won’t struggle during fasting.


As keto levels rise, magnesium will quickly get depleted. Too little magnesium can cause cramps and ‘brain fog’.


Daily multivitamins are a controversial issue in the health industry. Dr. Jason Fung, one of the intermittent fasting pioneers, believes that multivitamins don’t offer many benefits and can even be harmful.

He believes that the diseases we are plagued with nowadays are not caused by a lack of vitamins but by the type and amount of food we consume.

The general rule is to only take vitamins and minerals if you actually need them and have a deficiency. In the case of micronutrients, less is more. An overabundant supply of nutrients may cause conflicting reactions and is definitely a waste of money.


Fasting Supplements - Fish Oil
Fish oil needs to be taken with food.

So, if you do decide that you need multivitamins, make sure it doesn’t contain calories. For example, fish oil contains fat; fats contain calories, so there is a possibility that it can break your fast.

Make sure that the multivitamin does not contain any sugar as this will raise insulin. As soon as insulin increases, you are no longer fasting!

B-complex Vitamins

This includes riboflavin, niacin, biotin, and thiamine and is important in helping the body better absorb magnesium, potassium and other nutrients.


coffee beans Coffee is not a supplement, but it has many health benefits. Fasting and coffee go hand-in-hand for a lot of fasters.

In the case of fasting means without anything added like sugar, milk, MCT oil, etc. – can help you be more alert and focused when you go through a slump due to not eating.

According to one study, coffee can also help you perform better at the gym if taken before exercise.

And, it won’t kick you out of ketosis! So, although not a supplement, coffee can definitely help make your life a little easier while fasting.

Keep in mind that tannins and caffeine in coffee can possibly lower the absorption of other supplements.

Coffee may also add to the electrolyte imbalance in your body when fasting.

Easy Fasting Supplement Rules

Basically, follow these rules when you want to figure out if you can take a specific supplement while fasting:

  1. It does not contain protein, carbs, sugar or any macronutrients that need to be metabolized.
  2. Contains 20 calories or less
  3. Will not spike or trick your body into increasing insulin
  4. If it is a supplement that can be taken without food and does not break rules 1-3, it is okay. This includes Vitamin C, probiotics, activated charcoal, systemic enzymes, anti-microbial herbs, etc.

Know Your Body

Some people experience negative side-effects when taking dietary supplements while fasting – even if the supplement does not break any of the four rules mentioned above.

It is possible that they are sensitive to one of the ingredients contained in the supplement that can raise their heart rate, rise or drop blood pressure, cause cravings, increase fatigue, etc.

If that happens, it might be better to take the supplement after breaking your fasting or not to take it at all.

Supplements to Avoid

Apart from the four rules mentioned above, you basically want to avoid any supplements that should be taken with food. For example, Vitamin A, D, E and K are fat-soluble, which means they are best absorbed when taken with fat (food).

Taking these vitamins while fasting won’t necessarily kick you out of a fasting state; it just won’t be absorbed as well. In essence, wasting your money.


Fasting Supplements - Medicine
When possible, take your medicine during your eating window.

If you take prescribed medication, discuss with your doctor the effects of the drug on your hormones, especially insulin.

Also, if it is a time-sensitive type of medication, maybe try to take it during your eating window to make sure its effects don’t kick you out of a fasting state.


It is up to you whether you feel like fasting supplements are going to be beneficial for you. In my option, if you are doing a short fast, you may not need take supplements because you will get vitamins from your one meal.

Fasting for more than 3 days may be a different story though and you may want to consider taking fasting supplements then. After all, it comes down to your fitness and health goals, and in that regard everyone is different.

Want to give fasting a go? Check out our Awesome Juice Fasting Ultimate Guide for Weight Loss

This content has been Fact-Checked by a Certified Nutritionist in our Publishing Team. Learn more here.

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