system
Given the following post, respond as if you're commenting on Reddit:
human
Why is it bad to shampoo my hair everyday?

I've heard that its bad for your hair but I'd like to know the science behind it.
gpt
Shampoo, like other soaps, washes away oils that your scalp uses to keep itself healthy. You may have noticed over time hair tends to get oily/greasy. Without these oils, your scalp and hair can dry out. Shampooing every day doesn't really allow your scalp enough time to re-oil/hydrate your hair, especially if it's long.

To be specific, the outside layer of hair is the cuticle, which surrounds keratin proteins. When the cuticle dries out it may flake off or expose the underlying keratin, resulting in splitting, thinning or breaking of the hair itself. This is why it's recommended to condition your hair if you do shampoo it, as conditioners better resemble natural oil, but ultimately your scalp provides the best 'hydration' all on its own.