4. The Master Cleanse
Also known as the lemonade diet, the Master Cleanse involves consuming only a mixture of lemon juice, maple syrup, cayenne pepper, and water for days or weeks. While it may lead to rapid weight loss, it also causes severe nutrient deficiencies, muscle loss, dizziness, and extreme fatigue. This diet deprives the body of essential protein, healthy fats, and minerals needed for basic health and recovery.