Best Electrolyte Drinks for Fasting: An Honest Comparison

Every "best electrolytes for fasting" list you'll find online ranks products the same way: taste, price, brand reputation. Almost none of them actually pull the label and compare the numbers that matter for someone fasting specifically, and almost none of them look past the minerals at what else is riding along in the formula. So I did both here, including for Optimize. I'm not going to pretend our formula wins on every metric, because it doesn't. What I can tell you is exactly where each product is strong, where it's weak, what's actually in it beyond sodium and potassium, and which one fits your situation.

What Actually Matters When You're Choosing One

Before the comparison, here's the criteria I used, and why each one matters if you're fasting rather than just generally hydrating. For the fundamentals behind why these minerals matter and how much you actually need, I've written a complete guide to electrolytes for fasting here.

Zero calories, zero sugar. This is table stakes. If it has calories or triggers a real insulin response, it isn't fasting-safe, no other questions needed.

Real doses of sodium, potassium, and magnesium, listed individually. I've written before about why sodium is the electrolyte that depletes fastest during a fast, driven by the drop in insulin that happens a few hours into your window. Potassium and magnesium matter too, just on a slower timeline. A product that buries these behind a "mineral blend" instead of listing actual milligrams isn't giving you enough information to make a real decision.

What sweetener it uses, if any. Most electrolyte brands use stevia. I've written a full breakdown on stevia and fasting here, but the short version is that the research on whether it affects insulin is mixed, and even when it doesn't, it can keep sugar cravings alive during a window where the goal is often to let them fade.

Everything else on the label. Natural flavors, anti-caking agents, phosphate additives, and fortified extras all belong in this decision, not just the three electrolytes everyone talks about. This is the part most "best electrolytes" roundups skip entirely, and it's where I think the real differences between these products actually show up.

What the sodium source actually is. "Sodium" on a label usually means standard sodium chloride, the same refined salt in a saltshaker. That's fine, but it's not the same thing as a sea salt or mineral salt, which carries trace minerals along with the sodium.

Price per serving. Clean ingredients cost more. That's real, and it should factor into which one makes sense for your budget, not just your ideal formula.

The Comparison

LMNT

Sodium: 1,000mg
Potassium: 200mg
Magnesium: 60mg
Sweetener: Stevia leaf extract
Also contains: Citric acid, natural flavors
Price: About $1.50 per serving

LMNT leads the field on sodium by a wide margin, and if heavy sweating, hard training, or long fasted windows are your main concern, that matters. Magnesium is also solid here, better than most of the field. Worth knowing: the sodium comes from standard sodium chloride, not a sea salt or mineral salt, so you're getting sodium and chloride and nothing beyond that. The ingredient list itself is short, no anti-caking agents, no added vitamins, no phosphates, which is genuinely a point in its favor. Where it falls short is the same place every stevia-and-natural-flavors product does: natural flavors can legally cover dozens of undisclosed compounds, frequently including maltodextrin as a carrier, and LMNT doesn't list the flavor compounds or the carrier on the label, though it now discloses on its website that most flavors use 300 to 450 milligrams of maltodextrin as a carrier.

Redmond Re-Lyte

Sodium: 810mg
Potassium: 400mg
Magnesium: 50mg
Sweetener: Stevia leaf extract
Also contains: Citric acid, natural flavors
Price: Around $1.00–$1.20 per serving

Re-Lyte has the strongest potassium dose of the group by a wide margin, double LMNT's, and a very reasonable sodium number alongside it. Its sodium source is Redmond's Real Salt, an unrefined sea salt that carries 60-plus trace minerals along with it, a real point of difference from the plain sodium chloride in LMNT and Ultima. Like LMNT, the rest of the ingredient list is short, no anti-caking agents, no phosphates, no synthetic vitamin fortification. The tradeoff is the same natural flavors caveat: stevia and natural flavors both show up on the label, with the same undisclosed-compound and potential maltodextrin question as LMNT. If potassium is the piece you've been undersupplying, this is the strongest option here, and it's one of the cleaner labels in this comparison outside of that one gap.

Ultima Replenisher

Sodium: 55mg
Potassium: 250mg
Magnesium: 100mg
Sweetener: Stevia leaf extract
Also contains: Citric acid, potassium phosphate, natural flavors, plus fortified calcium, zinc, and manganese (as citrate, lactate, and ascorbate forms)
Price: About $0.47 per serving

Ultima is the cheapest option by a significant margin and carries the highest magnesium dose of the four. But I have to be direct here: 55 milligrams of sodium is not a meaningful amount for someone fasting. Given that sodium is the electrolyte your body loses fastest and most urgently during a fasted window, Ultima's formula reads like it was built for general daily hydration, not for the specific demands of fasting. The sodium is standard sodium chloride, same as LMNT, so no trace mineral upside there either.

Ultima's ingredient list is also the longest of the three competitor products, and it's worth knowing why. It uses potassium phosphate, a phosphate additive in the same category as the ones I've written about in other electrolyte comparisons. Research on phosphate additives has found they're absorbed by the body more efficiently than the phosphorus naturally occurring in food, and higher intake has been associated with cardiovascular risk markers and elevated blood phosphate, an effect of particular concern for anyone with reduced kidney function. One stick a day isn't a large dose on its own, but phosphate additives show up across a lot of processed food, and it's the kind of thing worth knowing you're adding to rather than finding out later. On the plus side, Ultima uses plant-based colors (beet juice, annatto extract) rather than synthetic dyes in its colored flavors, which is a genuinely good call I don't want to skip past just because the rest of the label has more going on. It's a fine everyday mineral supplement. I wouldn't rely on it to get you through a long fasted window without adding sodium from somewhere else, and I'd factor the phosphate and the longer ingredient list into that decision too.

Optimize

Sodium: 290mg
Potassium: 145mg
Magnesium: 30mg
Sweetener: None
Also contains: Real ginger, lemon peel, and vanilla bean for flavor, no natural flavors, no anti-caking agents, no phosphates
Price: About $1.50 per serving

I'll be straight about the numbers first: Optimize doesn't win this comparison of minerals on paper. LMNT and Re-Lyte both carry more sodium, Re-Lyte and Ultima both carry more potassium, and Ultima carries more magnesium. If the only thing you're optimizing for is the highest mineral dose per scoop, one of the other three gets you there in less servings. The sodium comes from real sea salt rather than refined salt, similar in spirit to what Re-Lyte does, though we don't market a specific trace mineral count the way they do.

What changes the picture is how often you can actually take it, and what's actually inside. Optimize is light enough to use more than once a day without creeping toward a daily ceiling most people never think about. General guidance caps sodium around 2,300 milligrams a day, and two servings of LMNT alone puts you at 2,000 of that before you've eaten anything. NIH's upper limit for supplemental magnesium is 350 milligrams a day, and two scoops of Ultima gets you to 200 before food. A second or third serving of Optimize, morning, pre-workout, before you break your fast, doesn't put you anywhere near those numbers, and it doesn't add phosphates, anti-caking agents, or an unnamed flavor blend on top of the minerals each time you use it. The higher-dose products on this list weren't really built to be taken that often, and that's the part nobody mentions when they lead with "more sodium is better."

That repeat use matters because the rest of the formula isn't just electrolytes, and it isn't processing aids either. L-theanine (150mg) is the amino acid behind the calm, clear-headed feeling people get from green tea, without the caffeine, and fasting fog is a real problem for a lot of people that none of the other three products here even attempt to address. Ceylon cinnamon has research behind it for blood sugar support, and steadier blood sugar is directly tied to fewer of the headaches and crashes that push people to break a fast early. Ginger and lemon support digestion, which matters most right before you break a fast, when your gut has gone quiet and needs to ease back in. LMNT, Re-Lyte, and Ultima are all built purely for hydration. None of them are thinking about that part of the window at all.

If you need maximum sodium in one serving because you're sweating hard or training fasted, Optimize isn't the strongest pick, and I'd rather say that plainly than talk around it. My honest suggestion in that specific case is to use Optimize with a pinch of sea salt added, which gets you the extra sodium without picking up any of the additives that come standard in the higher-dose competitors. But most people aren't using an electrolyte supplement for one serving on their hardest training day. They're using it multiple times through an ordinary fasting day, and that's what Optimize is actually built for: electrolytes plus mental clarity, blood sugar support, and digestion, without running into the ceiling, or the additive load, the higher-dose formulas carry if you use them the same way.

How to Actually Decide

If you train hard fasted or sweat heavily and sodium replacement is your main concern, my suggestion is to use Optimize with a pinch of sea salt. You'll get the increase in sodium without the added fillers and higher price tag. If potassium is the piece you've been undersupplying, Re-Lyte's 400 milligrams leads the field, and it's one of the cleaner labels here outside the natural flavors caveat. If you want the lowest price and don't mind a lighter sodium dose and a longer ingredient list, Ultima works as a general mineral supplement, though I'd pair it with added salt during a real fasted window and factor the potassium phosphate into that decision. If you want to take your electrolyte supplement more than once a day, whether that's morning, pre-workout, and pre-refeed, or you want mental clarity, blood sugar, and digestive support built into the same scoop instead of hydration alone, and you want the shortest possible list of things to second-guess, no natural flavors, no phosphates, no anti-caking agents, Optimize is the formula built for that.

These products are built around different priorities. The mistake is picking one because of a brand name or a flavor and never checking whether the full label, not just the mineral panel, matches what you actually want going into your body.

The Bottom Line

Pull the label before you buy, and read past the electrolyte numbers to the rest of the ingredient list. Look at sodium, potassium, and magnesium as actual milligram numbers, not just names on an ingredient list. Decide whether a sweetener matters to you, check for natural flavors and what might be riding along with them, and take note of phosphates, anti-caking agents, or added vitamins that weren't on your radar when you picked up the product for its mineral content. Then match the formula to what you're actually doing: hard training, a long fast, daily maintenance, or a cleaner label overall.

If you're looking for the option with real electrolyte doses, zero sweeteners, and the shortest ingredient list of the four, alongside functional ingredients that actually support the fast itself, Optimize is built for exactly that, and it's the one I'd point you to if label transparency and gut health are as much a part of your decision as the mineral count. If your priority is maximum sodium or potassium above everything else, I'd rather tell you that honestly and point you to the option that actually delivers it than sell you something that doesn't fit what you need.

Fuel your fast, feel your best.