Zero-calorie electrolytes for fasting
The best electrolytes for fasting are calorie free by the FDA rule, under 5 kcal per serving [8], sugar free, with no sugar ingredients, and they list sodium, potassium and magnesium. We apply the three label tests to every flavor, then rank on sodium near the middle of the sweat range plus the other two minerals.
On current label data the top three are Redmond Re-Lyte Energy Electrolyte Mix, UCAN Hydrate Electrolyte Drink Mix and 1st Phorm Hydration Daily.
15 of 148 products qualify; the top 10 are shown. Oldest label check: Sep 24, 2026. Oldest price check: Sep 24, 2026. How we ranked
The ranking
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Number 1: Redmond Re-Lyte Energy Electrolyte Mix
Why it ranks here
- 1,057 mg sodium per liter as mixed, in the high band (in the upper half of the typical sweat sodium range).
- 740 mg potassium per liter as mixed.
- $2.18 per 1,000 mg sodium.
- 85 mg magnesium per liter as mixed.
- Non-sugar sweeteners on the label: stevia.
Sodium per liter as mixed
Redmond Re-Lyte Energy Electrolyte Mix sodium per liter: 1,057 mg/L, in the High band (920 to 1,610 mg/L). Scale 0 to 2,500 mg/L.Redmond Re-Lyte Energy Electrolyte Mix label numbers per 12 fl oz and per liter Nutrient 12 fl oz Liter Sodium 375 mg 1,057 mg Potassium 263 mg 740 mg Magnesium 30 mg 85 mg Carbs 0 g 0 g Sugars 0 g 0 g Calories 0 kcal 0 kcal - Per serving
- $1.09
- Per 1,000 mg sodium
- $2.18
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Price checked Sep 24, 2026 at Redmond (Jar, 45 servings).
Label serving: 1 level scoop (6 g), mixed to 16 fl oz (473 mL).
Number 2: UCAN Hydrate Electrolyte Drink Mix
Why it ranks here
- 655 mg sodium per liter as mixed, in the moderate band (in the lower half of the typical sweat sodium range).
- 211 mg potassium per liter as mixed.
- $2.90 per 1,000 mg sodium.
- 106 mg magnesium per liter as mixed.
- Non-sugar sweeteners on the label: stevia.
Sodium per liter as mixed
UCAN Hydrate Electrolyte Drink Mix sodium per liter: 655 mg/L, in the Moderate band (230 to 920 mg/L). Scale 0 to 2,500 mg/L.UCAN Hydrate Electrolyte Drink Mix label numbers per 12 fl oz and per liter Nutrient 12 fl oz Liter Sodium 233 mg 655 mg Potassium 75 mg 211 mg Magnesium 38 mg 106 mg Carbs 0 g 0 g Sugars 0 g 0 g Calories 0 kcal 0 kcal - Per serving
- $0.90
- Per 1,000 mg sodium
- $2.90
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Price checked Sep 24, 2026 at UCAN (Jar, 30 servings (90 g)).
Label serving: 1 scoop (3g), mixed to 16 fl oz (473 mL).
Number 3: 1st Phorm Hydration Daily
Why it ranks here
- 529 mg sodium per liter as mixed, in the moderate band (in the lower half of the typical sweat sodium range).
- 1,057 mg potassium per liter as mixed.
- $7.40 per 1,000 mg sodium.
- 296 mg magnesium per liter as mixed.
- Non-sugar sweeteners on the label: stevia, monk fruit.
Sodium per liter as mixed
1st Phorm Hydration Daily sodium per liter: 529 mg/L, in the Moderate band (230 to 920 mg/L). Scale 0 to 2,500 mg/L.1st Phorm Hydration Daily label numbers per 12 fl oz and per liter Nutrient 12 fl oz Liter Sodium 188 mg 529 mg Potassium 375 mg 1,057 mg Magnesium 105 mg 296 mg Carbs 0 g 0 g Sugars 0 g 0 g Calories 0 kcal 0 kcal - Per serving
- $1.85
- Per 1,000 mg sodium
- $7.40
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Price checked Sep 24, 2026 at 1st Phorm (Box of 20 single-serve packets).
Label serving: 1 Packet (6.2g), mixed to 16 fl oz (473 mL).
Number 4: Key Nutrients Electrolyte Recovery Plus
Why it ranks here
- 233 mg sodium per liter as mixed, in the moderate band (in the lower half of the typical sweat sodium range).
- 529 mg potassium per liter as mixed.
- $4.04 per 1,000 mg sodium.
- 211 mg magnesium per liter as mixed.
- Non-sugar sweeteners on the label: stevia.
Sodium per liter as mixed
Key Nutrients Electrolyte Recovery Plus sodium per liter: 233 mg/L, in the Moderate band (230 to 920 mg/L). Scale 0 to 2,500 mg/L.Key Nutrients Electrolyte Recovery Plus label numbers per 12 fl oz and per liter Nutrient 12 fl oz Liter Sodium 83 mg 233 mg Potassium 188 mg 529 mg Magnesium 75 mg 211 mg Carbs 0 g 0 g Sugars 0 g 0 g Calories 0 kcal 0 kcal - Per serving
- $0.44
- Per 1,000 mg sodium
- $4.04
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Price checked Sep 24, 2026 at Key Nutrients (90-serving jar).
Label serving: 1 Scoop (4.3g), mixed to 16 fl oz (473 mL).
Why it ranks here
- 1,712 mg sodium per liter as mixed, in the very high band (saltier than typical sweat).
- 846 mg potassium per liter as mixed.
- $0.95 per 1,000 mg sodium.
- 106 mg magnesium per liter as mixed.
- Non-sugar sweeteners on the label: stevia.
Sodium per liter as mixed
Redmond Re-Lyte Hydration Electrolyte Powder sodium per liter: 1,712 mg/L, in the Very high band (1,610 to 2,500 mg/L). Scale 0 to 2,500 mg/L.Redmond Re-Lyte Hydration Electrolyte Powder label numbers per 12 fl oz and per liter Nutrient 12 fl oz Liter Sodium 608 mg 1,712 mg Potassium 300 mg 846 mg Magnesium 38 mg 106 mg Carbs 0 g 0 g Sugars 0 g 0 g Calories 0 kcal 0 kcal - Per serving
- $0.77
- Per 1,000 mg sodium
- $0.95
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Price checked Sep 24, 2026 at Redmond (60-serving jar).
Label serving: 1 level scoop (7g), mixed to 16 fl oz (473 mL).
Why it ranks here
- 116 mg sodium per liter as mixed, in the low band (less sodium per liter than the least salty sweat).
- 529 mg potassium per liter as mixed.
- $19.08 per 1,000 mg sodium.
- 211 mg magnesium per liter as mixed.
- Non-sugar sweeteners on the label: stevia.
Sodium per liter as mixed
Ultima Replenisher Daily Electrolyte Drink Mix sodium per liter: 116 mg/L, in the Low band (0 to 230 mg/L). Scale 0 to 2,500 mg/L.Ultima Replenisher Daily Electrolyte Drink Mix label numbers per 12 fl oz and per liter Nutrient 12 fl oz Liter Sodium 41 mg 116 mg Potassium 188 mg 529 mg Magnesium 75 mg 211 mg Carbs 0 g 0 g Sugars 0 g 0 g Calories 0 kcal 0 kcal - Per serving
- $1.05
- Per 1,000 mg sodium
- $19.08
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Price checked Sep 24, 2026 at Ultima Replenisher (20-serving stickpacks).
Label serving: 1 stickpack or 1 scoop, mixed to 16 fl oz (473 mL).
Number 7: Powerade Zero Sugar
Why it ranks here
- 676 mg sodium per liter as mixed, in the moderate band (in the lower half of the typical sweat sodium range).
- 225 mg potassium per liter as mixed.
- $1.72 per 1,000 mg sodium.
- No magnesium listed on the label.
- Non-sugar sweeteners on the label: sucralose, acesulfame potassium.
Sodium per liter as mixed
Powerade Zero Sugar sodium per liter: 676 mg/L, in the Moderate band (230 to 920 mg/L). Scale 0 to 2,500 mg/L.Powerade Zero Sugar label numbers per 12 fl oz and per liter Nutrient 12 fl oz Liter Sodium 240 mg 676 mg Potassium 80 mg 225 mg Magnesium not on label not on label Carbs 0 g 0 g Sugars 0 g 0 g Calories 0 kcal 0 kcal - Per serving
- $0.41
- Per 1,000 mg sodium
- $1.72
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Price checked Sep 24, 2026 at Target (8 x 20 fl oz bottles).
Label serving: 12 fl oz (2.5 servings per 28 fl oz container).
Number 8: SALTT Electrolyte Drink Mix
Why it ranks here
- 2,047 mg sodium per liter as mixed, in the very high band (saltier than typical sweat).
- 865 mg potassium per liter as mixed.
- $1.83 per 1,000 mg sodium.
- 376 mg magnesium per liter as mixed.
- Non-sugar sweeteners on the label: stevia.
Sodium per liter as mixed
SALTT Electrolyte Drink Mix sodium per liter: 2,047 mg/L, in the Very high band (1,610 to 2,500 mg/L). Scale 0 to 2,500 mg/L.SALTT Electrolyte Drink Mix label numbers per 12 fl oz and per liter Nutrient 12 fl oz Liter Sodium 726 mg 2,047 mg Potassium 307 mg 865 mg Magnesium 134 mg 376 mg Carbs 0.1 g 0.4 g Sugars 0 g 0 g Calories 2 kcal 6 kcal - Per serving
- $1.77
- Per 1,000 mg sodium
- $1.83
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Price checked Sep 24, 2026 at SALTT (30-stick pouch).
Label serving: 1 Stick Pack (6.6g), mixed to 16 fl oz (473 mL).
Number 9: 1st Phorm Hydration Sport
Why it ranks here
- 2,537 mg sodium per liter as mixed, in the very high band (saltier than typical sweat).
- 634 mg potassium per liter as mixed.
- $1.54 per 1,000 mg sodium.
- 63 mg magnesium per liter as mixed.
- Non-sugar sweeteners on the label: stevia.
Sodium per liter as mixed
1st Phorm Hydration Sport sodium per liter: 2,537 mg/L, in the Very high band (1,610 to 2,500 mg/L), above the 0 to 2,500 mg/L scale.1st Phorm Hydration Sport label numbers per 12 fl oz and per liter Nutrient 12 fl oz Liter Sodium 900 mg 2,537 mg Potassium 225 mg 634 mg Magnesium 23 mg 63 mg Carbs 0 g 0 g Sugars 0 g 0 g Calories 0 kcal 0 kcal - Per serving
- $1.85
- Per 1,000 mg sodium
- $1.54
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Price checked Sep 24, 2026 at 1st Phorm (Box of 20 single-serve packets).
Label serving: 1 Packet (7.1g), mixed to 16 fl oz (473 mL).
Number 10: Waterboy Daily Hydration
Why it ranks here
- 2,321 mg sodium per liter as mixed, in the very high band (saltier than typical sweat).
- 591 mg potassium per liter as mixed.
- $3.03 per 1,000 mg sodium.
- 84 mg magnesium per liter as mixed.
- Non-sugar sweeteners on the label: stevia.
Sodium per liter as mixed
Waterboy Daily Hydration sodium per liter: 2,321 mg/L, in the Very high band (1,610 to 2,500 mg/L). Scale 0 to 2,500 mg/L.Waterboy Daily Hydration label numbers per 12 fl oz and per liter Nutrient 12 fl oz Liter Sodium 824 mg 2,321 mg Potassium 210 mg 591 mg Magnesium 30 mg 84 mg Carbs 1.5 g 4.2 g Sugars 0 g 0 g Calories 0 kcal 0 kcal - Per serving
- $1.67
- Per 1,000 mg sodium
- $3.03
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Price checked Sep 24, 2026 at Waterboy (15-stick pouch).
Label serving: 1 Stick (3.0g), mixed to 8 fl oz (237 mL).
Side by side
| # | Product | Sodium per liter | Potassium per liter | Sugars per 12 fl oz | Calories per 12 fl oz | Cost per 1,000 mg sodium | Score |
|---|---|---|---|---|---|---|---|
| 1 | Redmond Re-Lyte Energy Electrolyte Mix | 1,057 mg | 740 mg | 0 g | 0 kcal | $2.18 | 95 of 100 |
| 2 | UCAN Hydrate Electrolyte Drink Mix | 655 mg | 211 mg | 0 g | 0 kcal | $2.90 | 90.4 of 100 |
| 3 | 1st Phorm Hydration Daily | 529 mg | 1,057 mg | 0 g | 0 kcal | $7.40 | 85.8 of 100 |
| 4 | Key Nutrients Electrolyte Recovery Plus | 233 mg | 529 mg | 0 g | 0 kcal | $4.04 | 75.1 of 100 |
| 5 | Redmond Re-Lyte Hydration Electrolyte Powder | 1,712 mg | 846 mg | 0 g | 0 kcal | $0.95 | 71.3 of 100 |
| 6 | Ultima Replenisher Daily Electrolyte Drink Mix | 116 mg | 529 mg | 0 g | 0 kcal | $19.08 | 70.9 of 100 |
| 7 | Powerade Zero Sugar | 676 mg | 225 mg | 0 g | 0 kcal | $1.72 | 66.2 of 100 |
| 8 | SALTT Electrolyte Drink Mix | 2,047 mg | 865 mg | 0 g | 2 kcal | $1.83 | 59.2 of 100 |
| 9 | 1st Phorm Hydration Sport | 2,537 mg | 634 mg | 0 g | 0 kcal | $1.54 | 50 of 100 |
| 10 | Waterboy Daily Hydration | 2,321 mg | 591 mg | 0 g | 0 kcal | $3.03 | 50 of 100 |
How we ranked
Any format qualifies if every flavor passes the calorie-free and sugar-free rules per serving and per reference amount, and the ingredient list contains no sugar, dextrose, maltodextrin or similar. The last test removes mixes that meet the calorie rule but still contain a small amount of sugar-type ingredients.
- Who qualifies
- Any format with less than 5 calories per serving and per 360 mL (the FDA calorie-free rule), sugar-free by the FDA rule, and no sugar in the ingredients list, in every flavor. The label must list calories, carbohydrate, sugars, sodium (above 0 mg) and potassium. We do not rank a product whose panel we could not read in full.
- How the score works
- Up to 50 points for sodium per liter as mixed, with full points at 920 mg/L, the middle of the typical sweat sodium range. Points fall in a straight line either side: half points at 230 and 1,610 mg/L, the ends of that range, and none at 2,300 mg/L or more. Up to 25 points for potassium per liter, with full points at 196 mg/L, the average potassium in sweat. 25 points if the label lists magnesium, because a fasting electrolyte stands in for the minerals food would supply. Ties go to the product whose label lists more nutrients, then to the lower cost per 1,000 mg sodium. A product with no recorded price goes last in a tie.
Scores use label data and published reference values only. Affiliate links and commission play no part. Read the full methodology.
What to look for in a fasting electrolyte
Calorie free, not just low calorie. The FDA calorie-free threshold is under 5 kcal per serving and per reference amount [8]. Labels show that as 0 or 5 calories. Low-calorie drinks allow far more.
No sugar-type ingredients. Maltodextrin and dextrose can hide in small amounts in sugar-free mixes. We check the ingredient list, not only the sugar line.
Unflavoured or lightly sweetened. Some fasting protocols avoid sweeteners altogether. The sweetener line under each product shows what, if anything, the label lists.
Sodium. Products range from lightly salted waters to salt-heavy powders. The gauge shows each against the typical sweat range, 230 to 1,610 mg/L [1].
FAQ
What electrolytes can you have while fasting?
That depends on the rules of your fast, which vary. If your rule is “no calories and no sugar”, the products above fit: each passes the FDA calorie-free rule, the sugar-free rule and has no sugar ingredients on the label. They are ranked by sodium, potassium and magnesium on the label.
Do electrolytes break a fast?
We cannot answer that for every kind of fast, and we have no study on it in our reference list. What we can show is that every product here has under 5 kcal per serving and no sugar ingredients on its label. Whether sweeteners matter for your fast is up to the approach you follow.
Can I drink electrolytes while fasting for blood work?
Ask the clinic or the person who ordered the test. Fasting instructions differ from one blood test to the next, so the person who ordered yours can tell you what is allowed. We compare product labels only and do not give advice on medical tests of any kind.
Are unflavoured electrolytes better for fasting?
They avoid sweeteners entirely, which matters if your fast excludes them. They also taste of salt, which some people find hard to drink in water. The sweetener line under each product shows whether it uses stevia, monk fruit, sucralose or nothing.
Oldest label check in this list (Redmond Re-Lyte Energy Electrolyte Mix): . Source (opens in a new tab)