I am suffering from extreme hair loss. Everyday a minimum of 400 hairs fall off. I'm highly disturbed. What can I do?

A doctor needs to examine you first. Crash diets and extreme weight loss is not healthy and may contribute to some hair loss.  A doctor may even order blood tests or make measurement such as a bulk test or miniaturization test looking at your hair under a microscope. Afterwards, the doctor may give you a diagnosis and explanation of your hair loss condition offering possible treatment plans which may or may not include surgery.

Thinning Hair -- Rogaine, Propecia, Viviscal, Progesterone, PRPIf you have thinning hair you really need an evaluation to see if it is genetic or from another cause like stress or autoimmune. If it is determined to be genetic there are many options and traditional treatments like rogaine foam and propecia pills can be used. I have great success in my practice using injectable progesterone and prp to the scalp. Postmenopausal women also benefit from spironolactone. I suggest seeing a dermatologist with expertise in hair loss. Best, Dr. Emer.

Shedding of more than 200 hairs per day is known as massive shedding, significant shedding or marked shedding. Without knowing all your story from start to finish, it's not possible to make a diagnosis. I would highly advise you see a physician who specializes in hair loss. In young women, the causes of massive shedding include telogen effluvium as well as other causes too. Your physician can help sort out the cause and then discuss appropriate strategies for regrowth. Weight loss can contribute as you've already alluded to buy a panel of blood tests will be needed. Stress, thyroid problems, low iron, diets, weight loss and medications can all contribute to hair shedding in young women. 

Women, unlike men, have many causes of hair loss that are not genetic and need to be evaluated by a doctor with a complete history and physical examination and many blood tests to isolate the cause of your hair loss. Simply, put, you need to get a good doctor and start from there.