Fasting Supplements: How to Optimize Your Fast

Fasting refers to controlled food restriction to switch the body from burning glucose for energy to using fat as a primary fuel source, a metabolic state known as ketosis. 

Intermittent and extended fasting is linked to several general and metabolic health benefits, and supporting the body with the right fasting supplements can greatly amplify its positive effects.

Discover five of the best fasting supplements and find out which ones may do more harm than good. 

What is fasting?

Fasting involves abstaining from food for a specific time period, prompting the body to shift its energy source.

Usually, the body uses blood glucose to generate energy for physiological processes and cellular functions. During fasting, when blood sugar levels decline, the body enters ketosis, a metabolic state that relies on fats for energy.

The breakdown of fat releases large amounts of ketones, a group of organic acids that serve as highly effective alternative fuel sources when glucose is sparse.  

Fasting has profound health benefits, including making it less challenging to lose weight, improving cognitive function, helping lower blood pressure, and stabilizing blood sugar levels. Cycles of fasting have also been linked to more robust immune system functions. 

A study published in Cell found that “Fasting has been shown to promote hematopoietic stem cell activation and regeneration of immune cells, modulate gut microbiota, and promote the T cell-dependent killing of cancer cells.”

The study also found that fasting-mimicking diets, such as the ketogenic diet, display similar benefits to time-restricted eating. This is likely due to the significant reduction in sugar and carbohydrate intake, which triggers ketosis and the subsequent release of ketones. 

Common types of fasting

There are several popular fasting methods, including intermittent, water, prolonged, and dry fasts.

Intermittent fasting is an eating pattern that alternates between time-restricted eating and fasting windows. The 16:8 intermittent fasting diet, one of the most popular choices due to its simplicity, involves 16 hours of fasting followed by an eight-hour eating window. 

Water fasting is a classic type of fast, usually lasting between 24 and 72 hours, during which only water is consumed, with no additional nutrients or supplements. 

Prolonged fasting refers to fasts that extend over several days, typically lasting more than 72 hours and sometimes continuing for a week or longer.

Dry fasting is a short-term and extreme fasting technique that restricts all food and liquid intake, including water, for up to 14 hours. 

Watch the video below to learn about some of the best supplements for intermittent fasting.

Can you take supplements while fasting?

Yes, you can take specific supplements to support your body’s nutritional needs during caloric restriction without disrupting the fasting state or interfering with its health benefits. 

“Taking targeted supplements while fasting helps support your health, especially if you lack adequate nutrient reserves,” explains Dr. Berg. “You don’t receive nutrients while fasting, which can lead to deficiencies, and supplementation is an excellent way to maintain overall well-being.”

While many supplements won’t break a fast or interfere with ketosis, it’s crucial to avoid those that can spike blood sugar or insulin levels to fully harness the benefits of fasting.

Signs you need more nutrients while fasting

While periodic and intermittent fasting is considered safe for healthy adults, those new to fasting may experience mild to moderate side effects as their body adapts.

A study published in Cureus found that the most common side effects of intermittent fasting were headaches, lethargy, mood swings, dizziness, and excessive urination.

Additionally, those who begin fasting after years of poor dietary habits may develop or exacerbate existing nutrient deficiencies. This can lead to more severe side effects, including muscle cramps, spasms, or even fainting.

To prepare your body for caloric restriction and replenish your nutrient stores, it’s recommended to follow a nutritious, low-carb diet plan, such as Healthy Keto, before starting a fasting regimen.

This helps prime your body for fat-burning, easing the transition into time-restricted eating and enhancing the overall fasting experience.

Best fasting supplements

While fasting, your body undergoes various changes, and the right supplements can help maintain hydration, support energy levels, and prevent nutrient deficiencies.

Here are five intermittent fasting supplements to support your health without breaking ketosis.

1. Minerals and electrolytes

During fasting, your body isn’t replenishing the essential electrolytes lost through sweat and urination, which can lead to a depletion of key minerals like potassium, calcium, magnesium, and sodium. 

These electrolytes are crucial for muscle function, nerve signaling, and maintaining fluid balance. Without adequate levels, you may experience symptoms such as fatigue, muscle cramps, and heart arrhythmias.

To avoid this, it’s important to take high-quality, sugar-free electrolyte supplements during fasting. This helps restore mineral balance and supports overall well-being, ensuring that your body functions optimally throughout the fasting process.

2. B vitamin complex 

B vitamins are water-soluble supplements that are readily absorbed by the body. 

Taking a B vitamin complex or unfortified nutritional yeast, which is naturally rich in these vitamins, can boost energy production and help support an effective metabolism while fasting.

3. Multivitamin

Another way to ensure adequate nutrition while fasting is to take a sugar-free, whole-food-based multivitamin that contains a broad spectrum of vitamins as well as minerals and trace minerals. 

Alternatively, you can choose natural nutrient sources such as raw wheatgrass juice powder, which is rich in vitamins, low in calories, and has minimal impact on ketosis.

Some people experience digestive discomfort when taking multivitamins on an empty stomach or can develop diarrhea, especially when taking high doses of vitamin C. 

Taking dietary supplements with your last meal prior to your fast can help minimize the risk of digestive issues while promoting adequate nutrition during time-restricted eating.

4. Cod liver oil

Cod liver oil is a rich source of health-promoting fats and won’t interfere with ketosis, making it an excellent fasting supplement. 

Although cod liver oils are more readily absorbed with food, these supplements are a rich source of fat-soluble vitamins A and D, as well as omega-3 fatty acids. 

Vitamin A and vitamin D support immunity, mitochondrial function, and energy production, while omega-3 fatty acids enhance cognition and promote mental clarity during fasting.

5. Medium-chain triglycerides oil

Medium-chain triglycerides (MCT) oil is easily absorbed and metabolized directly into ketones, providing a rapid energy source during periods of food restriction. 

MCT oil is commonly added to bulletproof coffee to promote focus and energy and can help extend fasting periods, thereby maximizing the health benefits of time-restricted eating.

Although MCTs and other fats, such as grass-fed butter, won’t kick you out of ketosis, they can slow fat burning, especially if consumed in excess. 

What supplements to avoid while fasting 

Consuming substantial calories or specific macronutrients, such as proteins and carbohydrates, elevates blood sugar levels and stimulates an insulin response, which disrupts ketosis and ends the fasting state.

Here are four supplements to avoid while fasting.

1. Gummy multivitamins

Gummy vitamins are commonly sweetened with cane sugar and contain protein from gelatin, which can quickly disrupt ketosis and break your fast. 

In addition, many of these supplements contain synthetic water-soluble vitamins, which are linked to potential side effects, such as gastrointestinal discomfort.

2. Branched-chain amino acids

Branched-chain amino acids (BCAAs) and other amino acids, such as L-glutamine, support protein metabolism, muscle growth, and energy production. 

However, amino acids can stimulate an insulin response, which can disrupt ketosis and diminish the benefits of fasting.

3. Protein powder

Protein powders are calorie-dense and break down into amino acids during digestion. Amino acids can stimulate insulin release, effectively interrupting the fasting state and counteracting its metabolic benefits.

Other animal-based supplements, such as collagen, are also better consumed during the eating window, as their protein content can disrupt fasting by triggering an insulin response and breaking the fasted state.

4. Sugar-containing supplements 

During fasting, it’s crucial to avoid supplements such as electrolyte powders that contain cane sugar or processed sweeteners such as maltodextrin, pectin, or fruit juice concentrate. 

These additives can quickly spike blood sugar and insulin levels, which will break the metabolic fasting state.

FAQ

Sources

1. Buono R, Longo VD. When Fasting Gets Tough, the Tough Immune Cells Get Going-or Die. Cell. 2019;178(5):1038-1040. https://pmc.ncbi.nlm.nih.gov/articles/PMC7474734/
2. Shalabi H, Hassan AS, Al-Zahrani FA, et al. Intermittent Fasting: Benefits, Side Effects, Quality of Life, and Knowledge of the Saudi Population. Cureus. 2023;15(2):e34722. https://pmc.ncbi.nlm.nih.gov/articles/PMC9998115/