You're 16 hours into a fast. Your head is starting to throb, your focus is gone, and you reach for an electrolyte drink to steady yourself — then freeze. Did you just undo the whole thing? It's one of the most common questions in fasting, and most answers skip the part that actually matters.
The short answer: do electrolytes break a fast?
No — electrolytes themselves don't break a fast. Whether a drink breaks a fast comes down to one thing: calories, specifically calories that provoke an insulin or digestive response. Sodium, potassium, magnesium, calcium and chloride are minerals, not fuel. On their own they carry no calories and give your body nothing to metabolize, so a genuinely calorie-free electrolyte drink leaves a fasted state intact.
The catch is that many "electrolyte" products aren't calorie-free. Anything built on cane sugar, dextrose, maltodextrin or fruit juice concentrate carries real carbohydrate, and that's what ends a fast. So the sharper version of the question isn't "do electrolytes break a fast" but "what else is in this particular stick pack?"
Why your sodium needs actually go up when you fast
Here is the part most fasting guides leave out. When you stop eating, insulin falls — that is much of the point of fasting. But insulin also tells your kidneys to hold on to sodium. When it drops, that signal weakens and your kidneys begin flushing sodium into your urine, a well-documented effect sometimes called the natriuresis of fasting. Reviewers have traced it to the fall in insulin, a rise in glucagon and ketones, and shifts in how the kidney's sodium–glucose transporters behave (Frontiers in Endocrinology, 2020).
The practical takeaway is counterintuitive: you tend to lose more sodium during a fast, not less. That daily loss — playing out while you are not eating any salt to replace it — is a common driver of the headaches, lightheadedness and flat, foggy feeling people call the "fasting flu." It is often a salt problem wearing a scary name.
Sodium is also what makes the water you drink actually count. It is the main electrolyte governing how much fluid your body retains; drink plain water without it and you can pass much of it straight through. In a controlled comparison of common beverages, drinks containing sodium stayed in the body measurably longer than plain water (Maughan et al., Am J Clin Nutr, 2016). During a fasting window, when you may be relying on water alone, that difference is easy to feel.
What to actually look for on the label
Three things decide whether an electrolyte drink fits a fast.
- Calories. This is the one that matters most. Look for a product that is genuinely calorie free — under 5 calories per serving.
- Sodium. Since fasting drives sodium out, a meaningful amount of sodium is a feature, not a flaw. A pinch-of-salt product won't do much.
- The sweetener. This is where the fine print lives. Zero-calorie sweeteners are generally treated as fasting-friendly, but any added sugar — even a small amount — is still sugar. Read the ingredient list, not just the front of the pack.
Where burbo fits a fasting window
burbo is calorie free, which is the first box a fasting drink needs to check. Each stick delivers 327 mg of sodium — a moderate amount that sits at the low end of the American College of Sports Medicine's 300–600 mg-per-hour range — alongside 200 mg potassium, 50 mg calcium and 100 mg of magnesium as magnesium bisglycinate, making burbo an excellent source of magnesium at 24% of the Daily Value. Sodium supports fluid absorption and retention, which is exactly the job you need done while you're relying on water alone.
On the sweetener: burbo is sweetened with OnoSweet, a zero-calorie form of Reb M, plus a trace of organic agave for flavor. Agave is a sugar syrup, present in a tiny amount — a fraction of a gram — which is why we describe burbo as calorie free. For the vast majority of intermittent fasters, a trace of agave inside an otherwise calorie-free stick is a non-issue; if you're doing a strict, clinical-style water fast where you want nothing but water and pure minerals, it's good to know it's there. Naming it plainly is part of what makes the rest of the label worth trusting.
On dosing, keep it simple. One stick in a full bottle of water covers a typical fasting window; on a long fast in the heat, roughly one stick per hour of active sweating is reasonable. Two sticks a day is comfortably fine and three is the practical ceiling — burbo carries a full slate of vitamins set against adult Daily Values, and past three sticks those add up faster than the sodium does. Always add each stick to a full bottle of water; more sticks should mean more fluid, never a more concentrated drink. And burbo is third-party tested for heavy metals — a heavy-metals screen specifically.
The practical takeaway
Electrolytes don't break a fast; calories do. Because fasting actively pushes sodium out through your kidneys, replacing it isn't cheating on your fast — it's often what makes the fast feel survivable. Choose something calorie-free with real sodium in it, read the ingredient list so you know exactly what you're drinking, and add it to a full bottle of water. That's the entire game.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. How this article was researched and written: our editorial standards.