Twice a day may be a bit much. I've been getting down from everyday for years to every other day and my hair seems much better for it. I started that frequently because I had super greasy hair through the teenage years.
My doctor told me at one point if you start reducing how much you wash it, your body will start to quit over producing oils that its trying to replenish right now. (within reason). I'd only go once a day for oily hair, more than that is stripping and drying out your hair too much.
I shower every single day because I work out and I wash with shampoo every other time. I will throw in some conditioner though. If I don't, my hair feels all matted and weird (I have super thick hair). Sometimes I can tell the difference when don't shampoo. It doesn't feel oily nor dry necessarily, but it has a rougher texture.
NOBODY should wash their hair daily. it washes out the natural protective oils and dries out your hair. you can do it once a week or twice weekly but no more than that. every few weeks or monthy deep condition your hair.
Some say you should only shampoo your hair every other day because it dries it out. But I usually do it everyday. It really depends on the type of hair you have. You might want to cut it down to once a day though just to see how it feels. :)
Depends on your hair type. Very short, thin, oily hair can be washed with shampoo once a day and even twice a day. Any medium to long hair should be limited to every other day, and all curly and most any long hair needs to be shampooed even less frequently. You might dry out your scalp, prevent proper hair growth, cause dandruff/dry scalp and cause damage to your hair like split ends.
if you have to wash your hair twice a day (because you work out and it gets oily sweaty ect) at least make the second wash with baby shampoo instead of your usual shampoo and see if that helps because no doubt it's drying it out if it's of any length.
Doing it two times a day is too much its stripping the natural oils from your hair. I try to only wash it once a day or every other day. I use dry shampoo for when it gets greasy and don't have time to wash it. Washing your body a lot is a good thing when I'm not washing my hair I use a shower cap and just wash my body.
Unless you're scalp is either really dry, really oily or you get it dirty from rubbing it in dirt, you shouldn't shampoo so often. Even if it is too dry or too oily, you don't need to shampoo twice a day.
The oils in your hair are much better are protecting your then shampoo, so let them do their thing for a day or two.