Which Supplements Can You Take While Fasting?

Last Updated: October 13, 2021

Man choosing between supplements at nutrition store.

Intermittent fasting is increasingly becoming a healthy lifestyle choice for many people. Fasting boosts your focus, incinerates body fat and helps to slow down the aging process.

During fasting periods it’s necessary to avoid eating foods or beverages containing calories, but can you take supplements while fasting? Yes, you can, but only certain ones.

Some supplements can actually break your fast, while others will not affect it. Here’s the low-down on which nutritional supplements to take while fasting, which to avoid, and the reasons why.

How Supplements Affect Fasting

Some individuals opt to use supplements while fasting to maintain sufficient levels of vitamins, minerals, and other nutrients. Fasting too often can result in nutritional deficiencies in those who have a diet that’s already low in vitamins and minerals.

Although developing nutritional deficiencies while fasting is not likely, it will mainly come down to how restrictive your fast is and for how long you maintain it.

If you do take supplements while fasting, it’s important to know which ones could break your fast. This includes any supplements that can trigger digestive function or spike your insulin levels.

The reason for this is that fasting helps your body enter ketosis, a metabolic state where you burn fat for fuel. When you fast, your body burns through stored glucose (from carbohydrates) and after that begins to burn fat for energy.

Therefore, you want to be aware of what supplements you take because some of them can break your fast and kick you out of ketosis. Also, some supplements won’t necessarily break your fast, but are meant to be taken with food – not on an empty stomach.

This is because certain ingredients are fat soluble (meaning they should be taken with fat-containing food in order for your body to absorb them), and if taken on an empty stomach they’ll pass through your body without having much benefit. Some examples include vitamins A, D, E and K.

Additionally, some supplements can cause nausea or stomach upset if taken without food.

Note: Be sure to talk to your doctor before adjusting your supplement schedule if you take prescription meds. Some medications should be taken with food or within a specific timeframe.

Supplements You Can Take While Fasting

The following intermittent fasting supplements are effective when taken without food, and/or are not likely to break your fast. 

  • Creatine: No matter if you use it pre- or post-workout, creatine is  unlikely to break a fast since it contains no calories and does not impact your insulin levels. (1)
  • Electrolytes: One important class of supplements for those who are fasting is electrolytes, which are nutrients that the body needs to maintain and regulate several essential bodily functions. During fasting and physical activity, the body can become depleted of electrolytes, such as sodium, potassium, magnesium, zinc, and calcium. Assuming the electrolyte supplement doesn’t any calories or sugars, it’s actually a good idea to take electrolytes while fasting – and they can even help prevent the side effects of the “keto flu” when switching over to ketosis.
  • L-tyrosine: L-tyrosine can elevate your mood and keep stress levels down, helping you feel stronger and mentally sharper while fasting. And even though it’s an amino acid, it’s not likely to break a fast when used in lower doses. What’s more, it’s meant to be taken on an empty stomach.
  • Prebiotics and Probiotics: These supplements normally don’t contain calories or digestible carbohydrates.(2) Moreover, certain probiotic supplements are supposed to be taken on an empty stomach, when there are lower levels of stomach acid. Look at the label on the probiotic/prebiotic supplement container to see the manufacturer’s recommendations.
  • Water-Soluble Vitamins: Vitamins B and C can be taken with water during a fasting period. Brands that don’t use sugar or added fillers will usually contain few calories, if any.  Vitamin C is normally OK to take on an empty stomach, but B-complex vitamins can cause nausea in some individuals when taken without food. If that’s the case for you, just take these vitamins after your fasting phase.
  • Pure Collagen: Although taking collagen could hamper autophagy, it shouldn’t interfere much with ketosis or fat burning during a fast.(3)
  • Fish and Algae Oil: When taken in normal doses, these supplements do not contain a significant number of calories or digestible carbs.

Supplements to Avoid While Fasting

The following supplements work best when taken with food, or will otherwise break your fast. It’s best to wait and take them during your eating window.

  • Gummy Vitamins: These typically are made with small amounts of sugar, protein, and even fat, all of which could break your fast.
  • BCAAs (Branched-chain amino acids): BCAAs and l-glutamine appear to trigger an increase in insulin that inhibits autophagy and can kick you out of ketosis.(4)(5).
  • Protein Powders: Whether it’s whey, casein, or whatever, protein powder has calories and triggers an increase in insulin, signaling your body that you’re not fasting any more (6). So wait to take your protein after your fasting period.
  • Chromium and Vanadium: These two minerals can cause your insulin levels to dip too low when fasting. If your blood sugar drops, you risk running into hypoglycemia, causing low blood sugar, bottomed-out energy levels, and horrible moods. Better to take these supplements after you’ve broken your fast.
  • Fat-Soluble Vitamins: This class of vitamins includes vitamins D, E, and multivitamins made with fat-soluble ingredients. These types of vitamins won’t dissolve in water, so you’ll need to take them with a meal. If you’re unsure, look on the label for directions.
  • Magnesium: Taking magnesium on an empty stomach can cause discomfort in some individuals.
  • Added Ingredients: Some supplements may contain certain ingredients that could break your fast, such as sugar, maltodextrin, pectin, or concentrated fruit juice – all of which contain sugar and calories.

Keto Charge website


While certain vitamins and supplements can be taken during fasting periods, some may not be as effective unless taken with food. Additionally, supplements containing calories or sugar are more likely to break your fast.

If you’re taking supplements that are meant to be taken with food, or cause you stomach upset when taken on an empty stomach, wait to take them during your eating window instead. Experimenting to find what works best for you is the key.

See Also: Top 10 Supplements For The Keto Diet


  1. https://www.ncbi.nlm.nih.gov/pubmed/12624482/?i=2&from=/11912564/related
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5385025/
  3. https://www.ncbi.nlm.nih.gov/pubmed/30881590
  4. https://www.bulletproof.com/supplements/dietary-supplements/supplements-while-fasting
  5. https://www.ncbi.nlm.nih.gov/pubmed/29281182
  6. https://www.ncbi.nlm.nih.gov/pubmed/16690869

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