Whether you’re fasting to improve your health or as part of a diet, you may have wondered whether taking your daily supplements breaks your fast. While taking a supplement during a religious fast primarily comes down to personal choice, you may be interested in knowing what the science says if you’re fasting on the keto diet or intermittent fasting diet. 

What are the benefits of fasting?

Some research suggests that intermittent fasting can help control blood sugar, reducing insulin resistance. This is useful, particularly for diabetics, in controlling blood sugar spikes and crashes. 

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Animal research also shows that fasting may have a role in brain health by enhancing cognitive function and protecting against neurogenerative diseases such as Alzheimer’s and Parkinson’s.

How supplements affect fasting

Fasting involves not consuming food for long periods. For example, intermittent fasting patterns may involve not eating for 12-16 hours per day, while others practice 24-48 hours once a week. 

Some fast as part of the keto diet for weight loss, while others use intermittent fasting to induce health benefits such as autophagy – in which the body gets rid of unwanted molecules. Research suggests autophagy may have a role in preventing liver diseases and controlling inflammation. 

Many people who choose to fast for health purposes take supplements to maintain their micronutrient levels while not eating. However, researchers fear that fasters may be at risk of vitamin deficiencies if they’re already not getting enough nutrients.

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Nevertheless, if you’ve committed to fasting for weight loss and other lifestyle goals such as increasing energy, knowing whether taking a supplement ‘breaks’ your fast is necessary.

Supplements likely to break your fast

  • Protein powders. Protein products are often high in calories. This sets off an insulin response, meaning your body will recognise that your fast is over. 
  • Vitamin gummies. These gummy forms of multivitamins often contain some fat or sugar, so taking them means you will have technically broken your fast.
  • BCAAs. Branched-chain amino acids, like protein powders, trigger an insulin response and impede the benefits of autophagy.
  • Certain ingredients. Multivitamins and other supplements that manufacturers with extra ingredients may be unsuitable for fasting. These include sugars, concentrated fruit juice and highly-processed fillers like maltodextrin and pectin.

Authentic Biotics products are free from fillers, bulking agents, and fillers, making them a more appropriate supplement while fasting. 

Supplements unlikely to break your fast

  • Multivitamins. Stick to brands like Authentic Biotics, which don’t use sugar, fillers, and other additives, to avoid consuming any calories and breaking your fast.
  • Creatine. Taking creatine supplements does not affect insulin secretion and is unlikely to break your fast.
  • Collagen. Taking pure collagen can inhibit autophagy slightly but is unlikely to impact ketosis while fasting. However, for those fasting for religious purposes or on a plant-based diet, note that many collagen supplements are made with animal products.
  • Probiotics/prebiotics. Both tend to be free of carbohydrates and calories.
  • Single-nutrient supplements. Individual vitamin or mineral supplements, such as those containing vitamin D, Vitamin B complex or magnesium, typically do not have significant calorific content. However, fat-soluble vitamins (vitamins A, D, E and K) are absorbed better by the body when combined with food. Therefore, it is perhaps better to take these when not fasting.

We recommend supplementing with a high-quality, high-bioavailability multivitamin focused on your specific health goals if you’re trying fasting for lifestyle reasons. Our favourites are Brain Health Goals, Immunity Goals and Bone & Joint Health Goals

We recommend checking the ingredients lists of any supplement you try, and ensuring you’re happy they won’t break your fast. If you’re unsure or using a supplement containing fat-soluble vitamins, it may be best to take your supplement during your eating hours.

The best supplements to take while fasting

B Vitamins are some of the most crucial nutrients to maintain while fasting for weight loss or other lifestyle goals. All 12 have a significant function in the body – from maintaining the nervous system to helping the body release energy from food. Unfortunately, many diets that involve fasting restrict the consumption of animal products, therefore risking deficiencies in vitamins such as B12. 

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Low B12 and magnesium levels can cause weakness, confusion, and tiredness – the last thing you need when you’re already restricting your food intake. Try including a high-quality supplement containing B-complex and magnesium, such as Brain Health Goals, to reduce your risk of deficiency.

If you’re fasting for medical reasons, however, it is important that you contact your doctor before starting a new supplement.

The takeaway 

Whatever the reason you’re fasting, it’s essential to maintain adequate nutrition – particularly since fasting may at first make you feel fatigued. 

Since some ingredients may break your fast by triggering an insulin response and stopping autophagy, it may be best to take supplements such as protein powders and BCAAs during your eating hours.