Why do we fast?

Actually god never says to have fast , human being himself started having fast.

When I was growing up we we did all of the things the Catholic church told us we were supposed to and one of them was fasting. So we did it. Like a lot of other things in my religion that eventually changed and fasting wasn't mandatory so most of us stopped. I understood at the time that we did it to show our love for God. I still love my God but show him in other ways.