Electrolytes on Carnivore: Sodium, Potassium and Magnesium

If you feel headachy, tired, dizzy or crampy in your first weeks on carnivore, electrolytes are the most likely culprit. Our Getting Started guide covers the quick fixes. This article explains the physiology, looks at how much of each mineral a meat-based diet actually supplies, and flags when you should not follow the usual advice.

Why low-carb changes your salt balance

Insulin does more than manage blood sugar. It also tells the kidneys to hold on to sodium: in classic experiments, raising insulin levels in healthy volunteers markedly reduced sodium excretion^[1]. When you cut carbohydrate drastically, insulin falls, and the kidneys let go of more sodium and water. This is called natriuresis. Stored glycogen, which binds water, is also used up. The result is the rapid early weight loss most people see, and, if sodium is not replaced, lower blood volume.

Lower blood volume explains the classic "keto flu" picture: lightheadedness on standing, headache, fatigue, poor exercise tolerance and sometimes palpitations. When the body is short of sodium it also tends to waste potassium, which can contribute to cramps and weakness.

How much is enough?

There is no trial that defines the ideal electrolyte intake on a carnivore diet. What we have is general population guidance plus practical experience from ketogenic diet research.

Sodium

Stephen Phinney, whose metabolic ward studies helped define ketogenic adaptation, described giving study participants about 3 g of extra sodium a day as broth, keeping total intake at roughly 3 to 5 g (3,000 to 5,000 mg) of sodium per day, and reported that this helped preserve exercise capacity and nitrogen balance^[5]. That is expert guidance from small studies, not an established requirement, and it is well above the 2,300 mg upper figure recommended for the general population^[2]. The rationale is that the low-insulin state increases sodium losses.

For scale, 2,300 mg of sodium is about one teaspoon of table salt^[6]. Many people on carnivore simply salt food to taste and add a cup or two of salted broth if they feel lightheaded. Common-sense signals that you may need more: dizziness when standing up, headaches, and fatigue that improves within 30 minutes of a salty broth.

Potassium

Meat and fish are genuinely good potassium sources, at roughly 315 to 330 mg per 3-ounce cooked serving^[3]. As a rough estimate from those figures, someone eating about 2 pounds (900 g) of cooked meat and fish a day would get in the region of 3,000 mg. People who eat little, or mostly fat, will get less. Potassium supplements need care: over-the-counter pills are limited to 99 mg each because of past safety problems with higher-dose potassium chloride, and high doses can dangerously raise blood potassium in some people^[3]. Food first; supplements only with medical advice.

Magnesium

Magnesium is where a meat-only diet most often falls short. Using the ODS figures of 20 to 26 mg per 3-ounce serving^[4], 900 g of cooked meat would provide only about 200 to 250 mg, below the RDA. Mineral water, some seafood and dairy help a little. Many people take a supplement; the upper limit for magnesium from supplements is 350 mg a day for adults, and higher doses commonly cause diarrhea, especially with oxide, carbonate, chloride and gluconate forms^[4].

Practical approach

1. Salt to taste and do not fear salt early on, unless you have one of the conditions below.
2. Drink to thirst. Forcing large amounts of plain water can dilute blood sodium further.
3. Eat enough meat. Under-eating is a common cause of low potassium and magnesium intake.
4. Use broth (bone broth or salted stock) as an easy way to add sodium and fluid.
5. Consider magnesium if you get cramps, poor sleep or constipation, staying within the supplement upper limit unless advised otherwise.
6. Check blood electrolytes at baseline and after a few months; see Labs to Track.

Important cautions

The "add more salt" advice is not for everyone. Talk to your doctor before changing your intake if any of these apply:

• Chronic kidney disease: the kidneys may not clear potassium and magnesium normally; potassium's usual intake targets do not apply to people with impaired excretion, and magnesium toxicity risk rises when kidney function is reduced^[3][4].
• Heart failure, significant fluid retention, or liver cirrhosis: extra sodium can worsen fluid overload.
• High blood pressure: some people are salt-sensitive. Blood pressure often falls on low-carb diets, but monitor at home rather than assuming.
• ACE inhibitors, ARBs, or potassium-sparing diuretics (such as spironolactone): these reduce potassium excretion and can cause high potassium, so avoid potassium supplements and salt substitutes unless your doctor approves^[3].
• Loop or thiazide diuretics: these increase losses of potassium and magnesium, so levels may run low^[4].
• Blood pressure medication in general: the combination of natriuresis and medication can cause dizziness or fainting. Doses sometimes need adjusting early on.
• Lithium: sodium and fluid shifts affect lithium levels; get your levels checked.

The bottom line

Low insulin makes the kidneys shed sodium, which explains most early "keto flu" symptoms. Generous salt and adequate food fix most of it. Meat supplies potassium well but magnesium poorly. If you have kidney disease, heart failure, or take blood pressure medication or diuretics, get individual advice before following general electrolyte guidance.