Is there extreme dieting in girls that causes loss of their periods?

Yes: If a girl has a very low body fat or has stressed her body by rapid weight loss - it can cause her to miss periods.

Yes: Anorexics who lose alot of weight- can lose their period and may have difficulty getting it back. Body Mass index should remain at 20 or higher. When body mass index falls below- you are at risk. Try not to restrict calories in extreme dieting. follow healthy diets and not fad diets, Do not lose more than one pound a week. Consult with a physician about a good weight for you.