Can You Take Supplements While Fasting?

Fasting is becoming an increasingly popular lifestyle approach for people consciously trying to have a healthier and more intentional relationship with food.

While some nutritional science experts may describe fasting as something of a diet fad, it seems to have an incredible staying power. It’s not that hard to understand why. Evidence-based clinical trials suggest that fasting for long periods may be not only an effective strategy for weight loss but also a way of potentially reducing the risk of various diseases and even prolonging one's life. However, additional research is needed to prove it conclusively.

However, every person who has tried fasting at least once in their life will tell you that while fasting, one wrestles with several questions. That’s why, in this article, we’ll explore the topic of supplements and vitamins, and how to take them if you choose to try out fasting.

What is intermittent fasting?

Simply put, intermittent fasting is an eating pattern that includes periods of eating and periods of not eating or virtually no-calorie intake. In other words, when you fast, you don’t eat for an extended portion of the day or — if you’re more advanced — the entire 24 hours.

This means that you cannot consume any calories during this time. You should drink plenty of water and can have black coffee or tea, but any foods are completely out of the question.

Why people practice intermittent fasting

The practice of fasting has existed for centuries. It is an essential part of many religions, including Christianity, Islam, Buddhism, Jainism, Hinduism, Judaism, and Taoism. In the 21st century, intermittent fasting has become popular for health reasons.

The idea is that the body can focus on maintenance and recovery while fasting rather than just digesting food. The increasing awareness of the potential benefits, such as weight loss, can also explain the popularity of fasting.

Another reason fasting is so popular is how easy and adaptable it is. Whether you follow a keto, carnivore, paleo, or other diet, you always have to cut out a significant portion of popular products. Fasting, on the other hand, emphasizes when you eat rather than what you eat.

How to correctly break a fast?

Every person who has tried fasting would probably tell you that not getting crazy and gorging yourself with food at the end of the fasting period requires some mental strength and discipline. After not eating for 14, 16, or 24 hours, all you can think about is food. However, it is generally recommended not to lose self-control when entering your eating window and opt to consume nutrient-rich foods.

The benefits of intermittent fasting

TOC: Benefits

As pointed out by a systematic review, intermittent fasting is associated with these potential benefits:

• Reduction of BMI and overall body weight
• Reduction of the total cholesterol, low-density lipoprotein (‘bad’) cholesterol, and triglyceride levels
• Reduction of fasting glucose levels and improvement in insulin resistance

Nevertheless, studies show inconsistent results regarding the effects of intermittent fasting on glucose metabolism.

Expert insights

For this section, we have asked nutritionist Sandra Vigelienė to share her perspective on the topic.

Some evidence suggests that such proposed benefits may be less attributable to the fasting pattern itself and more closely associated with the spontaneous calorie restriction that often occurs due to the reduced eating window. This suggests that intermittent fasting may not be inherently superior to other well-established dietary approaches. Given that the efficacy of fasting protocols is not conclusively established in terms of proposed benefits, it is essential to recognize that intermittent fasting may not be appropriate for everyone, particularly people with specific medical conditions or those with a vulnerable relationship with food.

As with any dietary intervention, assessing its suitability with your healthcare provider is advisable. Health decisions should always be personal, and the fasting approach is no exception.

Can you take supplements while fasting?

Vitamins are compounds that are essential for your well-being. Lacking vitamins can negatively impact your health, and several diseases and conditions have been linked to certain nutrient deficiencies. Various supplements have become an irreplaceable part of some people's diets.

For example, it’s estimated that up to three-quarters (74%) of Americans take supplements, with more than half (55%) taking them regularly, according to 2023 CRN Consumer Survey on Dietary Supplements data.

The question is, if you’re planning on trying intermittent fasting, should you continue using vitamins?

What is the role of vitamins and supplements?

Vitamins are typically obtained through dietary sources and are essential in supporting crucial bodily functions. If your diet is healthy and balanced, you should get a sufficient dose of vitamins through food.

However, over 2 billion people worldwide have some micronutrient deficiency, meaning that they don’t get enough vitamins from their daily diet, even the easily obtainable ones, such as vitamin C. Supplements can provide an option to combat nutrient deficiencies.

It must be stressed that no vitamin supplement can fully replace natural sources of vitamins, i.e., food. It’s better to take them as a part of a balanced diet. When used in this way, vitamin supplementation can help fill a great deal of possible nutrient gaps.

Should you stop taking supplements while fasting?

The issue with supplements in the context of fasting is that occasionally, they may contain some calories. Some have cane sugar, others — such as many forms of vitamin D — have oils. This means that in most cases, the calories from supplements would technically break a fast.

Supplements that do not contain calories will not affect a fast. You’re probably OK with using multivitamins and individual micronutrients such as vitamins C or B. Remember, doctors recommend taking some supplements with water and meals, for example, fat-soluble vitamins.

How to use supplements while fasting

If you’re using fasting methods such as 16:8 or 14:10, the solution is straightforward — take supplements that have calories or that are better absorbed with food when breaking a fast, i.e., with your very first meal after the fasting period. During longer periods of fasting, some may opt to only take supplements that contain no calories, which can be taken at any preferred time with water.

For this reason, you should always check the labels and make sure that the supplement in question doesn’t actually contain calories. For instance, gummy vitamins usually contain calories due to the fillers, although the vitamins themselves do not. Some more obvious examples are protein powder and oil-based supplements such as MCT oil. These supplements would break a fast due to the fact that they contain calories, thus increasing insulin levels.

It’s important to be mindful of your health goals and how fasting and supplements affect your body. For personalized advice, it is best to discuss the best approach with your provider to ensure safety and achieve individual needs.

The bottom line

Taking vitamins while fasting largely depends on the type of fasting method you follow and the composition of the supplements themselves.

While some supplements, such as protein powder containing calories, sugars, or oils, may break a fast, others, like individual micronutrients or multivitamins without additives, can typically be consumed without disrupting fasting benefits. In other words, some supplements need to be taken with food during the eating window, and others are fine during fasting.

Ultimately, intermittent fasting, healthy foods, and supplement use can complement each other when done thoughtfully, allowing you to maintain essential nutrient intake. Keep in mind that individual needs can vary; thus, it is important to adjust your approach based on your health goals and consult a healthcare provider when needed.