Free printable guide
The Australian Sodium & Hydration Cheat Sheet
One page you can stick on the fridge or save to your phone. How much sodium, potassium and magnesium people typically lose, and how to pick a drink that actually holds fluid.
Sodium is the main mineral in ordinary table salt. Your body uses it to hold on to fluid and to keep your nerves and muscles working. Potassium and magnesium are two more minerals you lose in sweat and urine. When you sweat hard, cut carbs, or go long stretches without eating, you let more of these minerals go than usual. This sheet is a plain-English guide to roughly how much leaves in each situation, and how to put a sensible amount back. The numbers are general typical ranges, not a prescription, and everyone is different.
How much you typically lose, by situation
Hot-weather training
Sweat is the big driver
- Sodium
- ~1000mg per litre of sweat
- Potassium
- ~200mg per litre of sweat
- Magnesium
- small amount
In the heat you can sweat roughly 1 to 1.5 litres an hour. Each litre of sweat carries very roughly a gram of sodium, so a long hot session can flush out a gram or more. That is why plain water alone can leave you feeling flat after a hard, sweaty workout.
Keto / low-carb
Your kidneys let go of more salt
- Sodium
- a few grams extra a day, early on
- Potassium
- worth topping up too
- Magnesium
- worth topping up too
When you eat very few carbs, the hormone insulin stays low. Low insulin tells your kidneys to hold on to less sodium, so more leaves in your urine. That is the fast water-weight drop in the first keto week. Low-carb guides commonly suggest adding a few grams of salt a day while you adjust.
Fasting
Same mechanism as low-carb
- Sodium
- add salt to water on longer fasts
- Potassium
- a common addition too
- Magnesium
- a common addition too
When you are not eating, insulin also drops, so you lose more sodium and water the same way as on keto. Many people doing longer fasts add salt or a sugar-free electrolyte powder to their water so they are putting back some of what is leaving.
These figures are typical general ranges from hydration and sweat research. Your own sweat rate and sweat salt content vary with your fitness, the weather and how acclimatised you are.
The concentration threshold: does the drink actually hold fluid?
Total milligrams on the label is only half the story. Sodium only does its fluid-holding job well once there is enough of it in each litre of water you drink. Research on how much fluid a drink helps you keep points to a useful working range, with the effect being weak below about 500mg of sodium per litre.
behaves like flavoured water ~900 to 1400 mg/L
the well-evidenced range
Plenty of ordinary sports drinks sit under that lower line. The practical takeaway: check how much sodium is in a serve, then check how much water the label tells you to add. A big number stirred into a large bottle can still land under the threshold.
How to read an electrolyte label in three steps
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1. The dose (milligrams per serve)
Look at sodium first, in milligrams per serve. Many products are politely dosed at 200 to 500mg, which is fine for a light day but low for hot training or low-carb eating. Then read how much water the label says to add, so you can sense-check it against the roughly 900 to 1400mg per litre range above.
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2. The mineral form
The same mineral comes in different chemical forms that dissolve and taste differently. For magnesium, citrate dissolves fully in water, while the cheaper oxide form barely dissolves. For potassium, the citrate form tastes cleaner than the chloride form, which can taste metallic. The ingredients list will name the form, for example magnesium citrate.
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3. The sugar
Check the sugar and carbohydrate lines on the nutrition panel, per serve. Many mainstream sports and electrolyte drinks carry several grams. If you are training fasted, doing keto or fasting, that added carbohydrate is usually the thing you are trying to avoid.
How Rawstone is dosed
Stir one serve into 750ml to 1 litre of water and it lands in that well-evidenced sodium range while staying pleasant to drink. Sweetened with Reb M, with no sugar. If you haven't heard of Reb M: most sugar-free drinks are sweetened with stevia, and the common cheap grade (called Reb A) is what leaves that bitter aftertaste. Reb M comes from the same stevia plant but tastes clean. It costs more, which is why most brands don't use it.
Want the launch-day discount too? Join the list.
Rawstone launches on Amazon Australia this summer. Sugar-free, 1000mg sodium, and the test certificate will be posted publicly from our first batch. Join the list for a launch-day discount code.
This sheet is general education about hydration physiology, not medical advice. Rawstone is a food supplement, not a medicine, and is not intended to diagnose, treat, cure or prevent any disease. If you have a condition that means you need to manage your sodium intake, talk to your doctor before using any electrolyte supplement.
rawstone.com.au/cheat-sheet · Clean, sugar-free electrolytes, Australian owned. Launching on Amazon Australia this summer.