Is this causing my brittle hair?

I've been taking a shower all this week but using hotter water. I sweat in the shower so I guess the oil naturally from my hair sweats along with it. Ive noticed that, every time I get out of the shower my hair is dry and brittle. Help please I thought of putting olive oil in my hair to keep the moisture in while I take a shower. P.S - Natural Ingredients only please.