Major shedding What it means: The average woman   may lose as many as 100 hairs a day, but if you suddenly notice fistfuls coming   loose when you brush or piles on your pillow, it may be a clue that you have   a hormonal imbalance called PCOS, or polycystic ovary syndrome. PCOS can trigger   your ovaries to produce too many androgens, or male sex hormones, and contribute   to hair thinning or hair loss.

Fine, limp texture What it means: If your once-thick   locks morph into thin strands, it could be a sign of hypothyroidism, a condition   by which the thyroid gland doesn't produce enough hormones, causing your metabolism   to slow down."The thyroid is the master gland that regulates your endocrine   system and it also impacts how hair is formed.

Hair that falls out only in patches What it means:   Losing hair in dime- and quarter-sized patches could be what's known as alopecia   aratha. It's thought to be an autoimmune condition where your immune system   attacks your body's own healthy cells and may be triggered by major life events   such as a pregnancy or illness.

Going gray early What it means: Genetics are mostly   to blame for those white hairs sprouting all over your head, and usually aren't   indicative of an underlying health problem. However, if you have a lot of grays   before age 35, some studies suggest you might be short on vitamin B12 and folic   acid. Researchers discovered that folic acid, vitamin B12 and sun exposure could   help re-pigment patches of both skin and hair that stopped producing melanin,   according to a study by the Department of Dermatology at University Hospital   in Uppsala, Sweden.

Dry, flaky scalp What it means: Dandruff can be   seriously embarrassing - it's definitely not an accessory you want to wear with   a little black dress during the holidays. Besides using too many products, those   little white flakes can also be the result of stress and anxiety.

Strands that break off easily What it means: Your   hair is made of a protein called keratin, and a lack of protein in your diet   can weaken tresses to the point that they snap. Vegans or vegetarians may be   especially at-risk since meats are one of the most common sources of protein.   If you're certain you're getting enough protein, the damage may be caused by   heat and overstyling.