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Best Fasting Supplements—What To Take And When

6 min read
a bunch of various supplements on a purple background_fasting supplemets
Melissa Mitri post Reviewer Melissa Mitri post Reviewer
Verified by Melissa Mitri
MS, Registered Dietitian, Former President of CT Academy of Nutrition & Dietetics

Table of Contents

Do I need to take any supplements while doing intermittent fasting?” This thought might have occurred to you at least once if you’re following an intermittent fasting plan. After all, people take various supplements for all kinds of reasons: to lose weight, gain muscle, and improve overall health. 

So, are fasting supplements necessary? Well, they can be. Since you’re limiting your food intake during fasting, you might be restricting not only the number of calories but also the amount of essential nutrients.

This is especially true for extended fasts such as 18/6 or 20/4 intermittent fasting. In such a case, you might need to take minerals or vitamins as supplements while fasting. You might also benefit from other supplements that aid weight loss or muscle gain.

Can you take these supplements while fasting without breaking the fast? What are the best fasting supplements, and when should you take them? We aim to find science-backed answers to these questions in today’s post.

Can You Take Supplements While Fasting?

You certainly can. You can take fasting supplements while you’re practicing intermittent fasting. However, the question is when to take them. 

You need to consider whether or not these supplements will break your fast and take them accordingly.

The basis of intermittent fasting is alternating fasting between fasting cycles. You’re not allowed to consume any calorie-containing foods or beverages—or supplements for that matter—during your fasting hours. 

If your supplements contain calories, they will certainly break your fast, but if they don’t, you can take them without any problem. We explain this in detail in one of our previous posts and you’re welcome to read it here for more information.

When to Take Supplements: Eating Vs. Fasting Window

As we explained earlier, the timing depends on the type of supplement you’re taking. 

If you’re taking a fasting supplement that doesn’t contain any calories, they are safe to be taken within the fasting window.

If it contains calories in the form of sugars, proteins, or fat, it should be taken within the eating window. For instance, some supplements can contain anywhere from 6.6-27.2 g of sugar [1]. Such supplements can increase blood glucose levels and knock your body out of ketosis, one of the hallmark benefits of intermittent fasting.

Another important thing you need to consider is whether the supplements are meant to be taken with food or on an empty stomach. Certain supplements, such as zinc and iron, are better taken before food (between meals, exactly) to increase their absorption [2] [3]

Certain other supplements, however, should be taken with food to maximize their absorption or avoid any stomach upset. For instance, fat-soluble vitamins should be taken along with a fatty meal for them to get absorbed [4]

Magnesium, on the other hand, can cause symptoms like diarrhea if taken on an empty stomach, so you need to pair it with food or take it after a meal [5].

5 Best Fasting Supplements to Boost Your Results

Here’s a list of the best fasting supplements you can add to your routine:

Vitamin Supplements

Since you’re limiting your eating window with fasting, there’s a risk of you not getting enough vitamins through your diet. There’s also evidence that fasting can cause a depletion of some vitamins, such as thiamine (vitamin B1), riboflavin (vitamin B2), and vitamin K [6]

If you’re taking vitamins while fasting, keep in mind that water-soluble vitamins (like B vitamins) are best taken during the fasting window, while fat-soluble vitamins (like vitamin D) should be taken during the eating window. However, be mindful of the ingredients in those vitamins as some vitamin gummies can contain gelatin and added sugar that can break your fast.

Mineral Supplements

As with vitamins, food restrictions can result in mineral insufficiencies. In fact, some scientific studies have reported that fasting can cause magnesium [7] and calcium [8] deficiencies. In such cases, you might need to replenish those reserves with supplements while fasting. 

Taking them won’t likely break your fast, but check carefully if they can cause stomach disturbances when taken on an empty stomach.

Probiotics and Prebiotics

If you’re not eating enough fruits and veggies during your eating hours, chances are you aren’t getting enough fiber, which is necessary to maintain a balanced gut microflora. In this instance, prebiotic and prebiotic supplements can help support a healthy gut. 

These supplements won’t disturb your fast as they don’t contain digestible carbohydrates. However, be mindful if you’re taking them in gummy form as they can contain gelatin and sugars that can break a fast.

You may also like: Best Time to Take Fiber Supplements

Amino Acids

Fasting has been shown to reduce the levels of certain amino acids such as lysine, threonine, arginine, and tryptophan [9]. Thus, amino acids are an important supplement that you can add to your fasting supplements stack. They can also help preserve muscle mass and build muscle as well. 

Branched-chain amino acids, along with vitamin B6, have also been shown to improve body composition by reducing the waist-to-hip ratio [10].


Research studies have demonstrated that cannabidiol can have appetite-reducing effects and can thus result in weight loss [11]. If you’re doing intermittent fasting with the aim of losing weight, you can take cannabidiol (CBD) as a supplement to boost your weight-loss results.

Do You Need Supplements On Intermittent Fasting?

Now, the main question is: do you need to take supplements while fasting? Not necessarily. 

You can take supplements if you have nutritional deficiencies or if you feel your diet is lacking most nutrients. However, if your diet is on point and you get enough macro and micronutrients through food, you will not need supplements. 

While there’s no harm in taking most mineral or vitamin supplements while fasting, keep in mind that some micronutrients, such as vitamins, can result in toxicity symptoms if you overdo it. 

Wrapping Up

You can take nutritional or weight-loss supplements to improve your intermittent fasting results and supply the necessary nutrients you may be lacking on a restricted diet. However, such supplements are not essential while intermittent fasting, unless you have a true deficiency.

While some supplements can break your fast, this is not the case with every supplement you take. You’ll therefore need to time your supplements accordingly to reduce the risk of interactions.

If you need to keep track of the type of supplements you’re taking and when to take them, you can log them in an all-in-one weight-loss app for easy monitoring. 

Disclaimer This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!

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