Assuming a healthy premenopausal woman, it suppresses the natural bodies hormonal balance. Then all kinds of nasty things happen, like osteoporosis <bone demineralization>, reduction of secondary sexual characteristics <breast, hips, and thighs become more masculine and extra abdominal fat deposits>, risk for high cholesterol and abnormal triglycerides increases>, vaginal atrophy, etc., ad nauseam.
What was your thought on why it would be beneficial?
It is used for treatment of certain sex-hormone responsive cancer, with controversy.