Does research support long-term water fasting safety?

Research on the safety of long-term water fasting is limited, and the available evidence suggests it can be dangerous if not conducted under strict medical supervision.

• While some studies show potential benefits like weight loss and blood pressure reduction, these studies often involve short-term fasting periods (24–72 hours) and highlight the need for careful monitoring and a controlled refeeding process.

• One study [1] involving an 8-day water fast showed significant metabolic changes in participants, including dehydration, increased ketogenesis, and electrolyte imbalances, suggesting that continuing the fast would be detrimental. This study emphasizes the importance of medical supervision during prolonged fasting, as the participants were carefully selected and monitored throughout the process.

• Another study [2], where participants fasted for 10 days, also reported a high dropout rate (almost 50%), further highlighting the challenges and potential risks of prolonged water fasting.

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[1] ... study of 2021 [2] ... study of 2022

Experts recommend against prolonged water fasting at home, as it differs significantly from medically supervised fasting where healthcare professionals can intervene in case of complications.

The limited research, combined with the potential for severe side effects like dehydration, electrolyte imbalances, muscle loss, and refeeding syndrome, suggests that long-term water fasting is not generally considered safe.

It is crucial to consult a healthcare professional before attempting any form of prolonged fasting to assess individual risks and ensure proper monitoring.