Taking only water for a day to two weeks forces the body to burn fat and switch on repair. It reliably lowers weight and blood sugar, and supervised longer fasts reduce blood pressure. Hopes for cellular clean-up, immune renewal, and longer life remain unproven in people. Risks rise with length: muscle loss, faintness, mineral imbalance, and danger when food returns. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Sodium (Na⁺) | 138–142 mmol/L | Detects hyponatremia from water intake without minerals |
| Potassium (K⁺) | 4.0–4.5 mmol/L | Guards against arrhythmia risk |
| Phosphate (PO₄) | 3.0–4.0 mg/dL | Earliest warning of refeeding syndrome |
| Magnesium (Mg²⁺) | 2.0–2.4 mg/dL | Supports cardiac and neuromuscular stability |
| Uric acid | < 6.0 mg/dL | Anticipates gout flares |
| Fasting glucose | 70–90 mg/dL | Tracks hypoglycemia risk, especially on medications |
| Creatinine / eGFR | eGFR > 90 mL/min/1.73 m² | Confirms kidney function is adequate for fasting |
| Blood pressure (orthostatic) | ~110–120 / 70–80 mmHg seated | Detects hypotension and fall risk |
Cadence: Vitals daily and key labs every 1–3 days; blood pressure and orthostatic checks twice daily, with electrolytes and phosphate checked at baseline, mid-fast, start of refeeding, and again at 1 week.