Prolonged fasting for more than 48 hours (such as extreme fasting) requires careful planning and execution to minimize risks and increase success rates. The following is a phased scientific guidance plan, but please note: **Fasting is not suitable for everyone**, especially those with basic diseases, pregnant women, a history of eating disorders or metabolic abnormalities need to consult a doctor first. --- ###**1. Pre-preparation (3-7 days before fasting)** 1. **Physical assessment** -Confirm that there are no contraindications such as diabetes, hypoglycemia, liver and kidney disease, and gastric ulcers. -Women need to avoid the menstrual period (fasting may exacerbate fatigue or hormone fluctuations). 2. **Gradually shorten the eating window** -Starting from 16:8 light fasting (16 hours on an empty stomach), gradually transitioning to 24-hour and 36-hour fasting to adapt the body to the ketone metabolism pattern. 3. **Adjust your diet** -Reduce refined carbohydrates (such as rice, pasta), increase high-quality fats (avocado, nuts) and protein, and reduce insulin fluctuations. -Supplement magnesium, potassium, and sodium (such as bone broth and sea salt) to avoid electrolyte imbalances during fasting. --- ###**2. The implementation stage of fasting (48+hours)** #### **1. Start-up period (0-24 hours)** -**Goal**: Deplete liver glycogen and initiate fat metabolism. -**Possible reactions**: Hunger, slight dizziness (normal), can be relieved by walking and meditation. -**Key measures**： -Drink 500ml of water (containing trace salt) every hour to avoid hyponatremia. - Avoid strenuous exercise and choose low-intensity activities such as yoga and walking. #### **2. Ketosis indication period (24-48 hours)** -**Body changes**: Entering a ketogenic state, fat is broken down into ketone bodies for energy, and hunger is weakened. -**Precautions**： -Monitor heart rate and blood pressure (be alert to orthostatic hypotension). -If you have severe headache, heart palpitations or vomiting, terminate fasting immediately and seek medical attention. #### **3. Extension stage (48+hours)** -**Potential risks**: Accelerated muscle breakdown and temporary decline in immunity. -**Only those with experience are recommended to try**： -Daily supplementation of multivitamins and electrolytes (such as sugar-free electrolyte tablets). -Keep enough sleep and avoid prolonged mental labor. --- ###**Third, the stage of re-eating (critical! ）** **Incorrect re-eating may cause "re-feeding syndrome” (electrolyte disorders, organ failure)** 1. **First meal (within 24 hours after fasting)**： -Start with a small amount of digestible foods: vegetable soup (no residue), coconut water, fermented yogurt. -Avoid foods that are high in sugar, fat, or fiber (which can easily cause diarrhea or soaring blood sugar). 2. **Follow-up 3 days**： -Gradually introduce low-fat proteins such as steamed vegetables, eggs, and fish. -The recovery of carbon water needs to be slow (such as starting from roots and roots) to avoid severe insulin fluctuations. --- ###**Fourth, tools and monitoring** -**Recording tools**: Use apps (such as Zero, Life Fasting) to track fasting time and body response. -**Health indicators**: Daily measurement of body weight, urinary ketones (test strips), resting heart rate, be wary of excessive dehydration or hypoglycemia. --- ###**5. Alternatives and warnings** -**Safer choice**: It is recommended to start with a 24-hour fast and try to extend it after gradually adapting. -**Warning signs**: If you experience persistent fatigue, confusion, or arrhythmia, stop immediately and seek medical attention. -**Long-term health**: Extreme fasting should not be frequent (≤1 time per month), combined with intermittent fasting, it is more sustainable. --- **Final reminder**: The core purpose of fasting is to restart metabolic flexibility, not to lose weight quickly. Be sure to take physical feelings as the first priority, and adjust your plan in time if necessary. If you have any concerns, it is recommended to do so under the supervision of a dietitian or doctor.