10/05/2026
Magnesium supports nerve signalling, muscle function and heart rhythm. During fasting, magnesium levels decline due to fluid loss and lack of dietary intake. Unlike sodium, this drop is more gradual and easier to miss.
Low magnesium shows up as muscle cramps, fatigue, headaches and poor sleep, even when everything else feels on track.
Daily needs are typically around 300 to 500 mg. Extended fasting provides none, and intermittent fasting may still fall short depending on food intake. Supplementing magnesium and other electrolytes makes a big difference to your health and well-being during fasting.