Best Electrolytes for Fasting

Last Updated

January 14, 2023

The practice of fasting has grown in popularity thanks to new research that has identified a number of possible health benefits associated with it. When performed correctly, fasting can contribute to healthy weight loss and possibly slow aging [1]. There are varying fasting techniques that align with different health goals and individual circumstances, so make sure you consult with a doctor before starting the practice. For an in depth discussion of fasting and its benefits we recommend the Tim Ferriss interview with esteemed scientist Dom D’Agostino out of University of South Florida Morsani College of Medicine.

Why Are Electrolytes Important During Fasting?

To identify the best electrolytes for fasting, it’s helpful to first understand why electrolyte supplementation is critical for the practice. Electrolytes support many bodily functions such as heartbeat and normal muscle function [2]. While electrolytes naturally leave the body, requiring dietary replacement, researchers have verified that during a prolonged fast sodium and potassium are depleted at higher levels than in a non-fasted state. The increased depletion of electrolytes is most prominent at the beginning of the fast before tapering off as the fast progresses [3].  Without proper supplementation, electrolyte levels can be depleted during a fast with consequences ranging from reduced cognition to significant decreases in physical performance. For further reading on this phenomenon check out our Optimal Hydration page.

Longer fasts may also induce ketosis with second order effects on electrolyte levels. A well researched side-effect of ketosis is the reduction of insulin levels which in turn cause the kidneys to release sodium and potassium from the body [4]. This can result in symptoms known as the “Keto Flu” which include headache, brain fog and fatigue [5]. All of which can be prevented with electrolyte supplementation.

 Can You Take Electrolytes While Fasting?

Electrolyte consumption while fasting will vary with your individual circumstances and may require some trial and error to see what regiment your body responds best to. Overall, electrolyte supplements won’t disrupt your fasted state if the product is mineral based with no carbohydrates. That said, there is some debate over the effects of stevia while fasting. If you are really passionate then we suggest performing a personal test with a blood sugar monitor since everyone will metabolize stevia slightly differently. 

One of the biggest factors dictating electrolyte consumption during fasting is activity levels. Exercise and movement increase perspiration which draws sodium and other minerals out of your body. It might seem obvious, but research has demonstrated that exercising while fasting will increase demands on electrolytes in your body compared to a fasted but sedentary state [6]. For this reason HydrationReview has elected to recommend two electrolytes for fasting: our overall pick and one for fasting when exercising.

The Best Electrolyte For Fasting: Ultima Replenisher

For fasting with limited or no exercise, we suggest Ultima Replenisher. 0 grams of sugar, 0 carbohydrates and 0 calories make it the perfect option for staying in a fasted state. It provides 55 mg of sodium, 250 mg of potassium, 100mg of magnesium and 65 mg of calcium. Ultima Replenisher was founded in 1996 in Ohio and has been providing high quality electrolyte products ever since. Given how much the HydrationReview team likes their product, we are hopeful that the brand will be around for another 25 years. 

In addition to having the ideal makeup of minerals, it’s one of the best tasting electrolytes on the market. Our favorite flavors are lemonade and raspberry. If those flavors don’t sound appealing, maybe grape, watermelon, blue raspberry or cherry pomegranate will do the trick. Ultima Replenisher is available in single serving packets and 20 serving tubs so you can leave packets in your bag and a tub in your kitchen so they are always at arm’s reach.

Click here to read our full review and learn about our team’s experience with Ultima Replenisher.

Ultima Replenisher packets next to an open water bottle.

Ultima Replenisher is an excellent everyday choice for those practicing fasting. You’ll stay ahead with 0 carbs and 0 sugar while still enjoying a delicious flavor. Pictured here are lemonade and raspberry. Both flavors ranked near based on our team’s feedback.

The Best Electrolyte for Fasting with Exercise: LMNT

LMNT provides a heavy dose of sodium (1000mg) along with potassium (200mg) and magnesium (60mg) at the expense of just 0-10 calories and 0g-2g of carbs depending on the flavor you choose. If you are concerned about Stevia then you can opt for the flavorless version. Citrus Salt and Raspberry Salt are the go-to flavors of the review team, though all are good in their own way. If you’re feeling brave, we recommend you try the Chocolate Salt variety – it was surprisingly well received by our reviewers and actually tasted like real chocolate. This might be a welcomed experience during an extended period without real food.

With the highest amount of sodium out of all electrolytes we’ve tested, LMNT is ideal for replacing lost electrolytes after a heavy sweat session combined with higher demands on electrolytes from being in a fasted state. Overall, our team found it tasted great and noticeably boosted physical performance.

Click here to read our full review and learn about our team’s experience with LMNT.

A handful of LMNT packets

LMNT comes in a variety of flavors that truly pair well with the 1000mg of salt. Our team found all of them to be great tasting, even the more edgy flavors like Chocolate Salt.


1Ferriss, Tim. “Dom D’Agostino on Fasting, Ketosis, and the End of Cancer (#117).” The Blog of Author Tim Ferriss, 16 Jan. 2020,

2Patrick, Rhonda. “FoundMyFitness Topic – Fasting.” FoundMyFitness, Accessed 24 Mar. 2022.

3“Fasting:”A Review with Emphasis on the Electrolytes.” ScienceDirect, 1 Feb. 1971,

4DeFronzo, RA. “The Effect of Insulin on Renal Sodium Metabolism. A Review with Clinical Implications.” Pub Med, Accessed 24 Mar. 2022.

5Kubala, Jillian M. “The Keto Flu: Symptoms and How to Get Rid of It.” Healthline, 3 Apr. 2018,

6“The Effect of Ramadan Fasting and Physical Activity on Body Composition, Serum Osmolarity Levels and Some Parameters of Electrolytes in Females.” National Library Of Medicine, Accessed 24 Mar. 2022.

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Products mentioned in this article

Ultima Replinisher

LMNT Electrolytes

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