Could a diet/lifestyle change cause girl problems?

Amenorrhea: In women and teens who diet heavily and lose weight too rapidly, menstruation or periods can become irregular, spotting, or no periods (amenorrhea). Dramatic wt loss can also lead to a risk of bone density loss known as osteoporosis. Discuss your recommended body wt for your height with your doctor and how many pounds per week is healthy for you to lose without resulting in medical problems.