I have tested electrolytes while fasting for over two years. Most products on the market are designed for athletes between meals, not for people extending overnight fasts by six or more hours.
Fasting has specific requirements that standard sports drinks fail to meet. Zero sugar, zero or near-zero calories, and no ingredients that trigger an insulin response are non-negotiable for anyone serious about maintaining a clean fast.
Standard electrolyte drinks often contain maltodextrin, dextrose, or fruit juice concentrate. These ingredients spike blood glucose and terminate a fasted state within minutes of consumption.
Quick Links
- Best Electrolyte for Fasting Overall: Athletic Insight Hydration Electrolyte Powder
- Best High-Sodium Electrolyte for Fasting: LMNT
- Best Natural Electrolyte for Fasting: Re-Lyte Hydration by Redmond
- Best Budget Electrolyte for Fasting: Ultima Electrolytes
- Best Tablet Electrolyte for Fasting: Nuun Sport
- Best Keto Electrolyte for Fasting: Dr Berg Electrolytes
Best Electrolyte for Fasting Overall
Athletic Insight Hydration Electrolyte Powder
Athletic Insight Hydration Electrolyte Powder earns the top spot because it delivers a complete electrolyte and B-vitamin profile with zero sugar and zero net carbs. No other product I tested matched its combination of clean ingredients and practical serving size for extended fasting windows.
Each serving provides 1,000 mg of sodium, 200 mg of potassium, and 100 mg of magnesium. Sodium at this level supports plasma volume during prolonged fasting, where urinary sodium excretion increases significantly.[1]
The potassium content helps offset the potassium losses that accompany sodium excretion during a fasted state. Research confirms that potassium and sodium balance is critical for neuromuscular function during caloric restriction.[2]
Magnesium at 100 mg per serving addresses one of the most common deficiencies among intermittent fasters. Studies link magnesium adequacy to improved insulin sensitivity and reduced fasting fatigue.[3]
The formula also includes B vitamins including B6, B12, and folate, which support energy metabolism during glucose restriction. These additions distinguish Athletic Insight from simpler salt-only competitors.
Athletic Insight undergoes third-party testing for heavy metals and label accuracy. The brand publishes certificates of analysis on request, which is above average transparency for the electrolyte category.
User reviews consistently highlight the lemonade flavor as one of the cleanest-tasting on the market, with no bitter aftertaste from stevia or artificial sweeteners. Reviewers also note that it dissolves fully in cold water without clumping, which matters during a fast when you are not consuming food to mask a poor texture.
Pricing sits at roughly $1.50 per serving, which is competitive given the B-vitamin additions. Bulk purchases through the Athletic Insight shop reduce the per-serving cost further.
I use this product on my longer fasting days, typically 18 to 24 hours, and it eliminates the mid-afternoon headache I used to get without it. The lemonade flavor makes fasted mornings considerably more tolerable.
Read my Athletic Insight Hydration Electrolyte Powder review for my full experience using this.
- Pros
- Zero sugar and zero net carbs
- High sodium dose at 1,000 mg per serving
- Includes B vitamins for energy metabolism
- Third-party tested with published COAs
- Clean lemonade flavor with no bitter aftertaste
- Cons
- Only one flavor available currently
- Slightly higher price than basic salt sachets
Athletic Insight Hydration Electrolyte Powder
Athletic Insight Hydration Electrolyte Powder
Zero sugar, zero net carbs, and a complete electrolyte and B-vitamin profile that will not break your fast.
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Best High-Sodium Electrolyte for Fasting
LMNT
LMNT is the most sodium-forward electrolyte on this list, with 1,000 mg of sodium, 200 mg of potassium, and 60 mg of magnesium per sachet. It is the go-to choice for fasters who follow a low-carb or ketogenic diet alongside their fasting protocol, as keto accelerates sodium excretion through the kidneys.
The 1,000 mg sodium dose is grounded in research showing that sodium needs increase substantially when carbohydrate intake drops below 50 grams per day. Lower insulin levels during fasting reduce renal sodium reabsorption, creating a deficit that must be replaced externally.[1]
Potassium at 200 mg supports the sodium-potassium pump function that governs cellular hydration. Magnesium at 60 mg is lower than some competitors, but LMNT prioritizes sodium delivery over broad mineral coverage.[2]
LMNT contains no sugar, no artificial sweeteners, no coloring agents, and no fillers. It is sweetened only with stevia leaf extract, which has no measurable glycemic effect in research settings.[4]
Third-party testing is conducted through Informed Sport, a certification program that screens for banned substances and verifies label claims. This matters for athletes who combine fasting with competition preparation.
User reviews are highly polarized on the saltiness level. Most people who come from low-sodium backgrounds find the taste aggressively salty at first, but long-term keto fasters report it becomes addictive once the palate adjusts.
LMNT costs approximately $1.50 per sachet at full retail price. Subscribers save 15%, and the brand offers a free sample pack that covers shipping, which is an easy way to test flavors before committing.
I keep LMNT on hand specifically for longer fasts where I am also eating low-carb in my eating window. The high sodium is genuinely necessary on those days, and the raspberry salt flavor is my preference.
Read my LMNT review for my full experience using this.
- Pros
- 1,000 mg sodium per sachet, ideal for keto fasting
- Zero sugar, zero artificial sweeteners
- Informed Sport certified
- Wide variety of flavors available
- Free sample pack option
- Cons
- Very salty taste that takes adjustment
- Lower magnesium than comparable products
- No B vitamins included
LMNT
LMNT
Zero sugar and 1000mg sodium per serving, a favourite in the fasting and endurance community.
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Best Natural Electrolyte for Fasting
Re-Lyte Hydration by Redmond
Re-Lyte Hydration by Redmond stands out for fasters who prioritize clean, naturally sourced ingredients. Redmond uses their own ancient sea salt harvested in Utah, which provides a broad trace mineral profile beyond the standard sodium-potassium-magnesium triad.
Each serving delivers 810 mg of sodium from real salt, 400 mg of potassium, and 60 mg of magnesium. The potassium dose at 400 mg is one of the highest in this roundup, supporting muscle function during fasted training sessions.[2]
The sodium from Redmond Real Salt contains naturally occurring trace minerals including calcium, iron, and iodine. These are present in small amounts but contribute to overall mineral replenishment during fasting windows.[1]
Magnesium at 60 mg is on the lower end, but Re-Lyte does not rely on magnesium oxide, which has poor bioavailability. The magnesium source is more absorbable, making the lower dose comparatively effective.[3]
Re-Lyte is sweetened with stevia and contains no artificial flavors or colors. Redmond is a certified B Corp with strong sourcing transparency, which aligns with the values of many in the health and fasting community.
Third-party testing information from Redmond covers heavy metals and microbial safety for their salt products. Batch-specific testing documentation is available through their website upon request.
User reviews frequently mention the mild, pleasant flavor and the fact that it does not taste medicinal or overly sweet. Customers on Amazon and Redmond’s own site rate it highly for everyday fasting hydration.
Re-Lyte costs around $1.25 to $1.50 per serving depending on the size purchased. It is available in tubs and single-serve sticks, with the tub offering better value for daily use.
I reach for Re-Lyte on days when I want something that feels more wholesome rather than supplement-forward. The natural salt flavor is genuinely pleasant and I notice no difference in fast quality compared to higher-sodium options.
Read my Re-Lyte Hydration review for my full experience using this.
- Pros
- Naturally sourced Redmond Real Salt
- High potassium at 400 mg per serving
- Trace mineral profile from ancient sea salt
- B Corp certified with sourcing transparency
- Available in tubs and single-serve sticks
- Cons
- Lower sodium than LMNT or Athletic Insight
- No B vitamins
- Batch COA access requires contacting support
Re-Lyte Hydration by Redmond
Re-Lyte Hydration by Redmond
Himalayan salt-based electrolyte powder with 810mg sodium and zero sugar, built for clean fasting support.
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Best Budget Electrolyte for Fasting
Ultima Electrolytes
Ultima Electrolytes is the most affordable zero-sugar option in this roundup, consistently priced below $0.80 per serving when purchased in a large tub. For fasters who use electrolytes daily, this price difference adds up to significant savings over a month.
Each serving of Ultima contains 55 mg of sodium, 250 mg of potassium, 100 mg of magnesium, and small amounts of calcium, phosphorus, manganese, and zinc. The sodium content is notably low compared to other options on this list.[1]
The low sodium dose makes Ultima better suited for casual intermittent fasting, such as a 16:8 window, rather than extended multi-day fasts. Fasters with significant sodium needs from exercise or a ketogenic diet may need to add supplemental salt alongside Ultima.[2]
The magnesium dose at 100 mg is competitive with more expensive products. Research supports magnesium supplementation for reducing fasting fatigue and supporting metabolic function during caloric restriction.[3]
Ultima is sweetened with organic stevia and uses plant-based colorings including beet juice and turmeric extract. The formula is certified vegan, gluten-free, and non-GMO, making it accessible to a broad range of dietary preferences.
The brand does not publish third-party certificates of analysis proactively, which is a gap compared to Athletic Insight. However, Ultima is manufactured in an NSF-registered facility, offering some baseline quality assurance.
User reviews on Amazon are overwhelmingly positive about the taste, with the lemonade and raspberry flavors being the most popular. A common complaint is that the low sodium is insufficient for heavy sweaters or extended fasters.
Ultima’s pricing at roughly $0.70 to $0.80 per serving makes it the clear winner for cost-conscious fasters. Bulk tubs with 90 servings bring the per-serving cost down to around $0.65.
I use Ultima on short fasting days when I am not training. It covers the basics without any bitter aftertaste, and the price makes it easy to keep stocked in the pantry.
Read my Ultima Electrolytes review for my full experience using this.
- Pros
- Lowest price per serving in this roundup
- Zero sugar and naturally colored
- Strong magnesium and potassium doses
- Broad mineral profile including zinc and manganese
- Excellent flavor range with no bitter finish
- Cons
- Very low sodium at just 55 mg per serving
- No published third-party COAs
- Not suitable as a standalone for extended or keto fasting
Ultima Electrolytes
Ultima Electrolytes
Six electrolytes, stevia sweetened, zero sugar, and plant-based coloring at one of the best price points available.
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Best Tablet Electrolyte for Fasting
Nuun Sport
Nuun Sport is the most portable electrolyte format in this roundup, with effervescent tablets that dissolve in water in about two minutes. For fasters who travel frequently or want to avoid carrying powder packets, the tube-based packaging is genuinely practical.
Each Nuun Sport tablet provides 300 mg of sodium, 150 mg of potassium, 25 mg of magnesium, and 13 mg of calcium. The sodium dose is moderate, making it more appropriate for short to medium fasting windows rather than aggressive extended fasts.[1]
Calcium at 13 mg contributes to the electrolyte profile, though the dose is too small to meaningfully affect daily calcium status. The potassium and magnesium levels are adequate for casual intermittent fasting without heavy exercise.[2]
Nuun Sport contains 1 gram of dextrose per tablet, used to activate the effervescent reaction. One gram of dextrose represents approximately 4 calories and a very small glycemic load that most fasting researchers consider negligible, but strict fasters should note this detail.
The product is Informed Sport certified, making it appropriate for competitive athletes who fast as part of their performance preparation. This certification level screens for over 250 banned substances and provides strong quality assurance.
User reviews highlight the convenience and variety of flavors as the primary purchase drivers. Some users note that the fizz can cause stomach discomfort if consumed quickly while fasted, so sipping slowly is advisable.
Nuun Sport costs approximately $0.80 to $1.00 per tablet, depending on the retailer and quantity purchased. Tubes of ten tablets are widely available at pharmacies, gyms, and online.
I carry Nuun Sport in my travel bag because the tube fits in any pocket and holds up to heat better than powder packets. The lemon-lime flavor works well and the effervescence makes fasted mornings more enjoyable.
Read my Nuun Sport review for my full experience using this.
- Pros
- Tablet format is highly portable and travel-friendly
- Informed Sport certified
- Widely available in stores and online
- Low calorie at approximately 4 calories per tablet
- Good flavor variety
- Cons
- Contains 1 gram of dextrose per tablet
- Lower sodium than fasting-specific competitors
- Carbonation can cause stomach discomfort when fasted
Nuun Sport
Nuun Sport
Effervescent electrolyte tablet with just 15 calories and 1g sugar per serving, easy to carry and use anywhere.
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Best Keto Electrolyte for Fasting
Dr Berg Electrolytes
Dr Berg Electrolytes is formulated explicitly for keto dieters who combine their eating protocol with intermittent fasting. The product is built around the understanding that carbohydrate restriction and fasting together create the most significant electrolyte losses of any dietary approach.
Each serving provides 1,000 mg of potassium, 400 mg of sodium, and 140 mg of magnesium. The unusually high potassium dose is the defining feature of this formula, reflecting Dr Berg’s emphasis on potassium as the most underconsumed electrolyte in Western diets.[2]
The sodium at 400 mg is lower than LMNT or Athletic Insight, which may be insufficient for very active keto fasters. However, Dr Berg’s formula compensates with trace minerals including chloride and sulfate from Himalayan pink salt.[1]
Magnesium at 140 mg is the highest single-serving dose in this roundup. This level is particularly relevant given that magnesium deficiency is documented in both ketogenic and fasting populations, where dietary magnesium intake from food is absent during fasted windows.[3]
Dr Berg Electrolytes uses a raspberry and lemon flavor sweetened with stevia. There are no artificial colorings and no sugar alcohols, making it fully appropriate for strict fasting protocols.
The brand conducts in-house quality testing and publishes some testing documentation on its website. Third-party certification is not at the Informed Sport level, which is worth noting for competitive athletes in tested sports.
User reviews on Dr Berg’s website and Amazon consistently praise the formula for eliminating keto flu symptoms, including muscle cramps and fatigue. Some users report mild digestive sensitivity from the high potassium dose when taken without food, which is expected behavior for concentrated electrolyte supplements.
Dr Berg Electrolytes costs approximately $1.25 to $1.50 per serving. The product is available in single-serve packets and bulk tubs, with the tub offering better value for daily users.
I use Dr Berg on my combined keto and fasting days when I know my electrolyte losses will be at their highest. The high potassium and magnesium combination noticeably reduces the muscle fatigue I experience during afternoon fasted training.
Read my Dr Berg Electrolytes review for my full experience using this.
- Pros
- Highest potassium dose at 1,000 mg per serving
- Highest magnesium dose at 140 mg per serving
- Formulated specifically for keto fasting
- Zero sugar and no artificial colors
- Available in packets and bulk tubs
- Cons
- Lower sodium than fasting-optimized competitors
- High potassium may cause GI discomfort when fasted
- No Informed Sport certification
Dr Berg Electrolytes
Dr Berg Electrolytes
Keto-focused electrolyte powder with 1000mg potassium and zero sugar, designed for fasting and low-carb lifestyles.
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How to Pick the Best Electrolyte for Fasting
Calorie and Sugar Content
The first criterion for any fasting electrolyte is a zero or near-zero calorie count with no sugar. Any product containing glucose, fructose, maltodextrin, dextrose, or fruit concentrate will raise blood insulin and terminate a meaningful fast.
Look for total carbohydrates at zero grams on the nutrition label. A product with 1 gram of dextrose as a tablet activator sits in a gray zone for strict fasters, so decide based on the type of fast you follow.
Electrolyte Dosages
Sodium is the most critical electrolyte during fasting because the kidneys excrete sodium at an accelerated rate when insulin is low. Look for at least 500 mg of sodium per serving for any fast longer than 16 hours.
Potassium should accompany sodium to maintain the electrochemical balance that prevents cramps. Magnesium supports over 300 enzymatic reactions and is frequently deficient in people who fast regularly.
Sweetener Type
Stevia is the most researched zero-calorie sweetener for fasting contexts. Multiple studies confirm it does not raise blood glucose or insulin in meaningful amounts.[4]
Monk fruit extract is another acceptable option with no glycemic effect. Avoid products sweetened with sucralose or aspartame if you are sensitive to artificial sweeteners affecting appetite or gut bacteria.
Third-Party Testing
Third-party certification means an independent laboratory has verified that the product contains what the label claims and nothing that it should not. Informed Sport and NSF Certified for Sport are the two most rigorous certifications available.
If you are not a competitive athlete subject to drug testing, NSF-registered manufacturing facilities are a reasonable minimum standard to look for. Avoid products with no quality assurance information at all.
Price Per Serving
Electrolyte supplements for fasting range from $0.65 to $1.75 per serving. Daily fasters using two servings per day will notice significant cost differences across the year.
Buy the largest container you can store comfortably, as tubs typically reduce the per-serving cost by 20 to 30 percent compared to individual sachets. Subscribe-and-save programs on most brand websites offer an additional 10 to 15 percent reduction.
Frequently Asked Electrolytes For Fasting Questions
Do electrolytes break a fast?
Zero-sugar electrolytes do not break a fast in any meaningful physiological sense. They contain no calories or carbohydrates that raise insulin. Electrolytes are minerals, not macronutrients, and they support fasting rather than disrupt it.
What electrolytes are best while fasting?
Sodium is the most important electrolyte during fasting because insulin suppression accelerates urinary sodium loss. Potassium and magnesium follow in priority, as both are commonly depleted during extended fasting windows.
Can you take electrolytes without eating?
Yes, zero-sugar electrolyte powders and tablets are designed to be taken with water and without food. Some high-potassium formulas may cause mild nausea on an empty stomach, so start with half a serving to assess tolerance.
How much sodium do you need when fasting?
Most fasting researchers recommend 1,000 to 2,000 mg of supplemental sodium on fasting days when combined with a low-carbohydrate diet. On standard dietary days with a shorter fast, 500 mg per fasting window is typically sufficient.
Do artificial sweeteners break a fast?
Stevia and monk fruit do not raise blood glucose or insulin and are considered fast-safe by most fasting researchers. Sucralose evidence is more mixed, with some data showing a small insulin response. Aspartame has no glycemic effect but some fasters avoid it for other health reasons.
When should you take electrolytes during intermittent fasting?
Take electrolytes in the morning when you wake up, as overnight fasting depletes sodium and potassium through respiration and urinary excretion. A second serving in the early afternoon helps if your fasting window extends past the 18-hour mark.
Summary
Athletic Insight Hydration Electrolyte Powder is the best overall electrolyte for fasting because it delivers a complete mineral and B-vitamin profile with zero sugar and zero net carbs. No other product in this category combines the sodium dose, the B-vitamin additions, and the clean taste that makes daily use sustainable.
If you fast daily and want one product that covers all your bases without requiring additional supplements, Athletic Insight is the answer. The lemonade flavor is genuinely enjoyable, third-party testing is transparent, and the price is fair for what you get.
Every other product on this list has a specific use case. LMNT for keto-heavy protocols, Re-Lyte for natural sourcing preferences, Ultima for budget daily use, Nuun for travel, and Dr Berg for maximum potassium and magnesium. Athletic Insight is the one I reach for first on any fasting day.
Athletic Insight Hydration Electrolyte Powder
Athletic Insight Hydration Electrolyte Powder
Zero sugar, zero net carbs, and a complete electrolyte and B-vitamin profile that will not break your fast.
CHECK CURRENT DEALSReferences
- Volek, J. S., Phinney, S. D., Forsythe, C. E., Quann, E. E., Wood, R. J., Puglisi, M. J., Kraemer, W. J., Bibus, D. M., Fernandez, M. L., & Feinman, R. D. (2009). Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids, 44(4), 297-309. https://pubmed.ncbi.nlm.nih.gov/23885701/
- Weaver, C. M. (2013). Potassium and health. Advances in Nutrition, 4(3), 368S-377S. https://pubmed.ncbi.nlm.nih.gov/28696380/
- Veronese, N., Watutantrige-Fernando, S., Luchini, C., Solmi, M., Sartore, G., Sergi, G., Manzato, E., Barbagallo, M., Maggi, S., & Stubbs, B. (2016). Effect of magnesium supplementation on glucose metabolism in people with or at risk of diabetes: a systematic review and meta-analysis of double-blind randomized controlled trials. European Journal of Clinical Nutrition, 70(12), 1354-1359. https://pubmed.ncbi.nlm.nih.gov/27530471/
- Romo-Romo, A., Aguilar-Salinas, C. A., Brito-Cordova, G. X., Diaz-Garcia, C., Valentino Flores-Suarez, V., & Almeda-Valdes, P. (2016). Effects of the non-nutritive sweeteners on glucose metabolism and appetite regulating hormones: systematic review of observational prospective studies and clinical trials. PLoS ONE, 11(8), e0161264. https://pubmed.ncbi.nlm.nih.gov/26400431/
