Electrolytes on Keto: Sodium, Potassium, Magnesium

The ketogenic diet alters how your body retains water and electrolytes. Within days of starting, you may notice changes in hydration status as glycogen stores deplete. Electrolytes—sodium, potassium, and magnesium—play critical roles in nerve function, muscle contraction, and fluid balance.

Why electrolytes matter on keto

When carbohydrate intake drops below 50 g daily, insulin levels decrease, prompting the kidneys to excrete more sodium. This creates a cascade effect where potassium and magnesium are also lost. A 2013 study found that very-low-carbohydrate diets significantly increase sodium excretion compared to low-fat diets (Bueno et al., 2013).

Sodium: The key electrolyte

Table salt provides sodium chloride. On keto, aim for 3-5 g sodium daily from broth, salted foods, or electrolyte supplements. At Tesco, a 500 g tub of sea salt costs £1.25. Those exercising may need more to account for sweat losses.

Potassium: Balancing act

Avocados, spinach, and mushrooms are rich sources. The NHS recommends 3,500 mg daily for adults. Deficiency can cause muscle cramps or palpitations.

Magnesium: Often overlooked

Dark chocolate, almonds, and pumpkin seeds contain magnesium. Symptoms of low levels include fatigue and leg cramps. A 300 g bag of almonds at Sainsbury’s costs £4.50.

What this means in practice

During summer months or when exercising, electrolyte needs increase. Carry salted nuts or add electrolyte tablets to water. The Keto Dieting app tracks mineral intake alongside macros.

Frequently asked questions

How do I know if I need more electrolytes?

Common signs include headaches, fatigue, muscle cramps, and dizziness. These often appear during the first week of keto adaptation.

Can I get enough electrolytes from food alone?

While whole foods provide electrolytes, those transitioning to keto or exercising intensely may benefit from supplements temporarily.

Are electrolyte imbalances dangerous?

Severe imbalances require medical attention. Most keto-related electrolyte issues are mild and resolve with increased intake.

The bottom line

Maintaining electrolyte balance—sodium, potassium, and magnesium—helps prevent keto flu symptoms and supports overall health. Track your intake, especially during adaptation or hot weather. If you’d rather not do the macro maths yourself, the Keto Dieting app does it for you on Google Play and the App Store. keto flu symptoms often resolve with proper electrolyte management, while hydration strategies vary by individual needs.

Educational only — not medical advice. This article is for general information. Speak to your GP before changing your diet, especially if you have type 1 or type 2 diabetes, kidney or liver disease, are pregnant or breastfeeding, or take medication for blood pressure, cholesterol, or blood glucose.

References

Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T (2013). Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. British Journal of Nutrition. https://doi.org/10.1017/S0007114513000548
Sumithran P, Prendergast LA, Delbridge E, et al. (2013). Ketosis and appetite-mediating nutrients and hormones after weight loss. European Journal of Clinical Nutrition. https://doi.org/10.1038/ejcn.2013.90