1. Sebab tak cukup tidur. 2. 4kg turun - kita tak tahu sama dia water weight, body fat or muscle. E.g., walaupun kita turun 6kg fat which is realistic and naik muscle 2kg, possible jugak and it can be Healthy. 3. Deficit jgn terlampau extreme, 300-400kcal deficit is just nice. 4. Long term sustainable fat loss >> short term extreme weight loss. 5. Yang penting, Muscle retention + fat loss. Not weight loss especially muscle mass.