For older adults or lean people, calorie-restriction method may not be safe. Calorie-restriction diet may cause following side effects: menstrual irregularities, hormonal changes or reduced bone density. If you want to use calorie-restriction method, you will need to consult your doctor.
Excessive calorie restriction can even lead to depression, dizziness, anemia, irritability or lethargy. If you decide to adopt a calorie-restriction diet, you must first ensure getting enough vitamins, calcium and other needed nutrients, and you also need to maintain regular physical activity and healthy lifestyles.