Supplementing with the right nutrients during your intermittent fast will help you improve your athletic performance and gain a competitive advantage at a faster rate. With so many supplements on the market it's hard to know which supplements you can take so you remain in the fasted state.
When your body produces an insulin response to ingesting caloric energy, you quickly go from a fasted state to a fed-state, therefore it's important to know which and what type of supplements you can take while fasting to gain the competitive advantage you're looking for.
In this article, we will reveal what supplements are best for intermittent fasting, which supplements to avoid during your fast, and how to optimize your fasted state.
What Is Intermittent Fasting and How It Works
Intermittent fasting (IF) is an eating pattern that cycles between periods of fasting and eating. Rather than focusing on what you eat, intermittent fasting emphasizes when you eat — and it’s become one of the most popular strategies for improving body composition, insulin sensitivity, and metabolic health.
There are several popular methods of intermittent fasting, including:
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16:8 — Fast for 16 hours, eat during an 8-hour window
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18:6 or 20:4 — Extended fasting periods for deeper fat-burning benefits
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OMAD (One Meal A Day) — 23 hours of fasting with one large meal
How Intermittent Fasting Works
When you fast, your body experiences a metabolic shift. Without incoming calories, insulin levels drop, and your body switches from using glucose (carbohydrates) as fuel to burning fat stores for energy. This transition increases fat oxidation, enhances mitochondrial function, and can even trigger autophagy, a cellular cleanup process that clears out damaged cells and promotes longevity (Mizushima & Komatsu, 2011).
Fasting also helps regulate hormones like ghrelin and leptin, which control hunger and satiety, making it easier to adhere to a calorie deficit and support long-term weight loss or maintenance goals.
While fasting offers these benefits on its own, pairing it with fasted workouts can significantly amplify fat loss and performance — as long as you don’t disrupt your fast with the wrong supplements.
The Best Supplements to Take for Intermittent Fasting Workouts
Working out while intermittent fasting can improve metabolic flexibility, enhance fat burning, and help you build a leaner, more defined physique. But to maximize your performance and protect your muscle mass during fasted workouts, strategic supplementation is essential.
Here are the best supplements to take while training fasted — all of which can help fuel your body without breaking your fast.
1. Kre-Alkalyn
Kre-Alkalyn is a patented, pH-corrected form of creatine phosphate that eliminates the bloating and water retention typically associated with conventional creatine monohydrate.
During fasted workouts, your body can't rely on glucose for energy. Instead, it utilizes ATP (adenosine triphosphate), which is stored in the muscle as creatine phosphate. Supplementing with Kre-Alkalyn supports ATP regeneration, allowing for more explosive power, strength, and endurance — even when carbohydrate stores are low.
Studies show that Kre-Alkalyn can increase creatine phosphate stores in muscle tissue by up to 20%, enhancing strength and muscle growth during high-intensity exercise. (Buford et al., 2007)
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📖 RELATED ARTICLE: The Best Form Of Creatine: Kre-Alkalyn vs Creatine Monohydrate
2. Beta-Alanine
Beta-Alanine is a non-essential beta amino acid proven to increase muscle endurance by buffering lactic acid accumulation. Lactic acid is the compound responsible for the burning sensation during high-intensity workouts and a major contributor to fatigue.
By increasing carnosine levels in muscle tissue, beta-alanine helps delay fatigue, increase time to exhaustion, and improve training volume — all critical for athletic performance while fasting.
Research published in Amino Acids confirms that beta-alanine enhances high-intensity performance, especially in exercises lasting 60 to 240 seconds. (Hobson et al., 2012)
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📖 RELATED ARTICLE: Beta-Alanine: The Best Supplement For Increasing Muscle Endurance
3. L-Glutamine
L-Glutamine is the most abundant conditionally essential amino acid in the body. During intense training, your glutamine levels become depleted, which can hinder muscle recovery, decrease strength, and prolong soreness.
Supplementing with glutamine while fasting can help maintain a positive nitrogen balance, preserve lean mass, and accelerate post-workout recovery.
Research supports L-Glutamine for reducing muscle soreness and improving muscle repair following intense workouts. (Cruzat et al., 2018)
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📖 RELATED ARTICLE: L-Glutamine: The Best Supplement For Muscle Recovery And Soreness
4. Citrulline Malate
Citrulline Malate is a powerful combination of the amino acid L-Citrulline (from watermelon) and malate (from apples). It enhances aerobic energy production, delays muscle fatigue, and boosts nitric oxide levels for improved blood flow.
A study in the British Journal of Sports Medicine found that 6g of Citrulline Malate daily reduced muscle fatigue and increased oxidative ATP production by 34%, with a 20% increase in phosphocreatine recovery after training (Perez-Guisado & Jakeman, 2010).
✅ RECOMMENDED PRODUCT: Citrulline Malate (Unflavored, 100 Servings)
📖 RELATED ARTICLE: 3 Clinically Proven Benefits Of How Citrulline Malate Can Improve Your Training
5. Collagen
Collagen protein is the ideal protein powder for intermittent fasting. Unlike whey protein, which contains trace amounts of carbs and fat, hydrolyzed collagen is pure protein, making it less likely to spike insulin or break your fast.
Collagen supports joint, tendon, and ligament health — essential when training fasted — and contains high levels of glycine, proline, and hydroxyproline, which promote tissue repair and skin elasticity.
Collagen supplementation may reduce joint pain and improve athletic performance, according to research in Current Medical Research and Opinion. (Clark et al., 2008)
✅ RECOMMENDED PRODUCT: Hydrolyzed Collagen Protein (Unflavored, 45 Servings)
📖 RELATED ARTICLE: The Ultimate Guide To Collagen Protein - Benefits, Uses
6. EAA & Electrolytes
Intra-workout formulas with essential amino acids (EAAs) and electrolytes are vital for hydration and muscle protection during fasted training.
Electrolytes like sodium, magnesium, potassium, and calcium help regulate muscle contractions, nerve function, and hydration status — especially important in the early morning when you're most depleted.
EAAs help kickstart muscle protein synthesis and combat catabolism from fasted training, preserving muscle mass while supporting recovery.
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📖 RELATED ARTICLE: What Are Essential Amino Acids
7. Thermogenics (Fat Burners)
Fat burners are most effective when taken in a fasted state, making them ideal for intermittent fasting workouts.
Thermogenics work through:
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Fat oxidation: mobilizing stored fat for energy
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Increased core temperature: boosting caloric burn
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Metabolism stimulation: enhancing resting energy expenditure
Ingredients like green tea extract, forskolin, and garcinia cambogia are backed by science to support increased fat loss and thermogenesis. (Hursel & Westerterp-Plantenga, 2010)
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📖 RELATED ARTICLE: What Is Thermogenesis?
Training while intermittent fasting can be incredibly effective — but only if you're fueling your body strategically. These fast-friendly supplements can help you maintain performance, support recovery, and enhance fat-burning without breaking your fast.
For best results:
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Choose unflavored, calorie-free formulas
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Use clinically dosed ingredients
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Stay consistent with your supplementation strategy
What Supplements to Avoid While Intermittent Fasting
While certain supplements can support your energy, strength, and recovery without breaking your fast, others contain ingredients that trigger digestion, raise insulin, or contain calories — ultimately defeating the purpose of fasting.
Here’s what to avoid if you want to stay in a true fasted state:
1. Supplements with Proprietary Blends
Most pre-workout formulas fall under this category. Proprietary blends allow companies to hide the exact amounts of each ingredient, which often means:
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Minimal doses of clinically effective ingredients
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Added fillers, sugar, or hidden carbs
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Stimulants or additives that spike insulin or digestion
This lack of transparency makes it nearly impossible to know whether a supplement will break your fast or support your goals.
📖 RELATED: What Is A Proprietary Blend? 5 Reasons Why You Should Avoid Them
2. Carbohydrate Supplements
Carbohydrate powders — even those marketed as “clean” or “natural” — are designed to boost glycogen, trigger insulin, and deliver fast-acting energy.
Taking carb-based supplements during your fast will:
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Raise blood glucose and insulin levels
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Halt ketone production and fat oxidation
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Kick your body out of the fasted state
This includes supplements like:
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Dextrose
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Maltodextrin
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Highly branched cyclic dextrin (HBCD)
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Gainers or intra-carb drinks
3. Flavored Protein Powders and Meal Replacement Shakes
Even if you opt for whey isolate or plant-based protein, many formulas still contain:
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Added sweeteners (sugar, sucralose, or stevia)
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Fats and carbohydrates
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Flavoring agents that trigger digestion
These may be fine post-workout or during your feeding window, but during a fast, they can spike insulin and disrupt fat-burning.
4. Pre-Workout Supplements with Stimulants or Sugars
Pre-workouts often contain:
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Proprietary blends (see above)
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Added sugars or artificial flavors
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Stimulants that increase cortisol levels unnecessarily
Fasting already elevates cortisol slightly to help mobilize stored fat for energy. Adding excessive stimulants or metabolic triggers may increase stress, reduce recovery, and break your fast — especially if the supplement includes flavoring, citric acid, or maltodextrin.
Summary: Supplements to Avoid While Fasting
To maintain your fast and get the most from your workouts, avoid these supplement types during your fasting window:
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❌ Proprietary blend formulas
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❌ Carbohydrate powders
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❌ Flavored protein powders
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❌ Pre-workouts with sugars or unknown ingredients
If your goal is fat loss, improved metabolic health, or preserving lean muscle while training fasted, stick with unflavored, calorie-free, and clinically dosed supplements.
Need help identifying fasting-safe supplements? Explore fasted-friendly formulas here →
Conclusion: These Supplements Are The Best To Increase Performance While Fasting
Can you take supplements during intermittent fasting? Yes! Proper supplementation while in the fasted-state is paramount to obtaining the desired results you want and meeting your athletic aspirations. Keep in mind, however, that in order to derive the benefits of intermittent fasting, you must remain in the fasted state during your workout. Supplement with products that are unflavored, proprietary blend free, and that use clinically dosed and proven ingredients. If you're looking to gain a competitive edge, clock faster times, row harder, sprint faster, lift heavier, and hammer more reps, then optimizing your nutrition is key, especially during your fast, to crush your goals.
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