Can You Take Supplements While Fasting? Everything You Need to Know

Fasting means abstaining from food for a specific period. There are many ways to do it, the most common being intermittent fasting, where you alternate between eating and fasting windows. Extended fasting lasts 24 hours or more, like the 48-hour fast. Another popular method is time-restricted eating, where you consume all your meals within a set time window each day. A more flexible approach is dirty fasting, which allows for small amounts of calories during the fasting period, like adding creamer to coffee or sipping bone broth. Each type of fasting has its own set of guidelines. Still, all share the goal of giving your digestive system a break to trigger various health benefits.

Some benefits of fasting include weight loss, better metabolic health, graceful aging and enhanced brain function.^[1] When you fast, your body shifts from using glucose as its primary energy source to burning stored fat, which can lead to weight loss and improved insulin sensitivity.^[2] Fasting also promotes autophagy, a process where the body cleans out damaged cells and regenerates new ones, potentially lowering the risk of certain diseases.^[3] Additionally, fasting can improve inflammation and heart health by lowering blood pressure, cholesterol, and triglyceride levels.^[4] And that’s why at Bulletproof, we are big fans of adding intermittent fasting to your wellness routine.

So, can you take supplements while fasting? It might seem counterintuitive, but some fasting supplements may help your body burn fat for fuel. Read on for your guide to taking supplements while fasting.

What Supplements to Take During a Fast

Knowing when and how to take supplements can help you maintain the benefits of your fasting regimen. The impact of supplements depends on factors like their composition and the type of fast you’re following. While some supplements may offer benefits, such as supporting nutrient intake during fasting, others might introduce calories or stimulate digestion, potentially interfering with fasting.

You should be able to take the following intermittent fasting supplements on an empty stomach. If you experience unwanted effects, like digestive discomfort, make sure to pay attention to how you feel. If that happens, try taking them 20-30 minutes before your meal instead.

• Creatine: Whether you take it before or after a workout, creatine won’t break your fast because it has no calories. However, while creatine doesn’t change your insulin levels, it might affect how your body handles sugar, leading to higher blood sugar levels during fasting.^[5] If you’re fasting to keep your blood sugar stable, you should be aware that creatine might have an impact, even though it doesn’t technically break your fast.
• Electrolytes: Taking electrolytes while fasting is vital because your body loses essential minerals like potassium and sodium more quickly at first.^[6] Fasting and the shift into ketosis can lead to rapid water loss and increased excretion of these electrolytes. Replenishing them helps prevent imbalances and manage side effects like fatigue or muscle cramps. Find out why electrolytes are great keto fasting supplements with our keto supplements guide.
• L-tyrosine: Taking L-tyrosine is unlikely to break your fast, especially if the supplement is in its pure form and doesn’t contain added sugars, fillers or calories. L-tyrosine is an amino acid that doesn’t directly impact insulin levels or disrupt the metabolic processes associated with fasting.^[7]
• Probiotics: Probiotics are beneficial gut bacteria that support overall health.^[8] If your probiotic has no calories, it won’t break a fast but watch out for higher-calorie options like gummies. While you can take some probiotics on an empty stomach when stomach acid levels are lower, you can take others with food. Always check the label on your probiotic supplement for the manufacturer’s recommendations.
• Prebiotics: Prebiotics are generally non-digestible fibers that support gut health, and they don’t usually trigger an insulin response or disrupt the fasting state.^[9] Bulletproof InnerFuel Prebiotic contains 0 grams of sugar and 0 grams of net carbs, and it mixes easily in hot or cold liquids. Try it with black coffee in the morning.
• Water-soluble vitamins: Can you take vitamins while fasting? You can take vitamin C with water during a fasting period. It is absorbed quickly with water and doesn’t require food for proper absorption.^[10] However, taking them on an empty stomach can sometimes cause mild discomfort, so it’s something to be mindful of based on your body’s response. On the other hand, vitamin B12 should be taken with protein to stimulate its intrinsic factor in the stomach, which aids absorption in the intestines.^[11]

Some supplements are more effective when taken with food because certain nutrients are better absorbed when paired with fats or other meal components. Next, explore which supplements to take with food to maximize their benefits and avoid potential stomach discomfort.

What Supplements to Take with Food

Do supplements break a fast? Yes, some do. Others are best absorbed with food in your stomach. Here’s what you need to know.

• Amino acids: L-glutamine and branched-chain amino acids (BCAAs) are usually a no-go while fasting because they can kick you out of ketosis by raising your insulin levels.^[12]
• Curcumin and omega-3 fatty acids: Supplements like Turmeric Curcumin Complex and Bulletproof Omega Krill Complex are more accessible for your body to absorb when taken with food. So, have them during your eating window.
• Fat-soluble vitamins: This category includes vitamins D, E and multivitamins containing fat-soluble ingredients.^[13] These vitamins don’t dissolve in water, so take them with a meal. If you’re not sure, check the directions on the label. If you need more clarification, check the directions on the label. If you’re taking Bulletproof Vitamins A-D-K, make sure to take one soft gel daily with food.
• Gummy vitamins: These vitamins are usually sweetened and made with gelatin, which contains protein—which means they’ll likely break a fast.
• Iodine: Take your kelp powder or potassium iodide capsules with food for maximum absorption.
• Magnesium: Some people can experience an upset stomach when they take a magnesium supplement on an empty stomach. Pairing it with a meal helps buffer the supplement and makes it easier on your digestive system.
• Protein powder: Does collagen break a fast? Whether you consume whey or collagen protein, any protein powder breaks a fast because it contains calories and triggers an insulin response. Save your protein powder for your eating window.
• Zinc and copper: These two minerals work better together, so you’ll often see them combined in a pill form, like in the Bulletproof Zinc with Copper supplement. It would be best to take a zinc and copper supplement with food to improve absorption and reduce the risk of stomach irritation. Zinc can cause nausea or discomfort when taken on an empty stomach. Taking these minerals with food helps ensure they are absorbed more efficiently, maximizing their benefits for your body.

The Science Behind Fasting Supplements

To reap the most significant health benefits of intermittent fasting, avoid consuming anything that breaks your fast. That includes calorie-containing foods or beverages and supplements that trigger digestion or spike your insulin levels.

Fasting helps your body enter ketosis, a metabolic state where you burn fat for fuel. Your body needs energy to function. When you skip meals, it burns through your stored glucose (from carbohydrates) and then starts burning fat for energy. Fasting may also cause your body to secrete a protein called fasting-induced adipose factor (FIAF), which signals that it’s time to burn fat.^[14]

All that to say, you want to be mindful when supplementing because some of them will break your fast and kick you out of ketosis. Others won’t necessarily break your fast—but they aren’t meant to be taken on an empty stomach.

Why is that a big deal? If your supplement is meant to be taken with food, but you take it without, it’ll pass through your body without being completely absorbed. Others risk making you feel digestive discomfort.

If you take prescription medications, talk to your healthcare provider before you switch up your supplementation routine. Some medications must be taken within specific timeframes. For others, taking them on an empty stomach can interfere with their effects. Follow your healthcare provider’s instructions regarding how and when to take your medication. If you’re unsure how a medication might interact with fasting, consult your doctor or pharmacist for guidance.

What About Drinks Like Coffee, Tea and Bone Broth?

What can you drink while fasting, besides water? Black coffee and unsweetened tea both technically have calories, but the amount is minimal (less than five calories) and unlikely to break your fast. If you’re a fasting purist, stick to water. If you want caffeine, coffee and tea are fine.

Bone broth is a popular keto-fasting supplement because it’s satisfying and replenishes nutrients and minerals during a fast. It has minimal calories and protein and no carbohydrates, so a small amount won’t dramatically impact the ketogenic or fat-burning benefits of fasting. But to maximize your fasting benefits, save the bone broth for your eating window.

The bottom line: Yes, you can use some supplements while you’re fasting. If your vitamins and medication upset your stomach or need to be taken with food, take them during your eating window. Experiment to find what works for you and helps you thrive.