Common causes of osteoporosis include: firstly, aging, especially in women after menopause. Secondly, a diet lacking in calcium and vitamin D, which means the bones don't get enough nutrients. Additionally, lack of exercise, smoking, and excessive alcohol consumption can increase the risk. Certain diseases and long-term use of some medications can also lead to osteoporosis. Maintaining a healthy lifestyle, getting enough calcium and vitamin D, and exercising moderately can effectively prevent osteoporosis.