What it looks like: Bald spots or visible scalp, more hair in the drain after shampooing, less drying time
Why it happens: Several reasons, including hormone changes and slower protein production.
When it happens: About 80 percent of women will be affected by hair loss and 30 percent of 30-year-old women already have this problem.
What you can do: Increase protein intake with foods like cheese and lean meats and talk to your doctor about vitamins to strengthen hair cuticles.
Product to try: Pantene AgeDefy Advanced Thickening treatment ($19, at mass retailers), which boosts volume