Common causes of osteoporosis include: 1. Aging: Bone density naturally decreases with age. 2. Hormonal changes: Especially in women after menopause, lower estrogen levels lead to bone loss. 3. Lack of calcium and vitamin D: These nutrients are crucial for bone health. 4. Lack of exercise: Physical activity helps strengthen bones. 5. Certain diseases and medications: Such as hyperthyroidism or long-term use of corticosteroids.