This sounds ridiculously similar to the book Every Day
I haven't read the book yet but the synopses are basically identical. This seems like way too big of a coincidence...
When you grow up, your heart dies.
You are right, the premise is almost identical to David Levithan's book 'Every Day'.
Having read the book, the stories do play out very differently, though. And unlike Alex in this show the central character in the book, only known as A, identifies neither as male nor female. He/she also doesn't just switch bodies, but actually inhabits other people's lifes for a day.
The funny thing is that the first episode of this show was released on August 15, 2012 while the book was published on August 28, 2012, so clearly neither format could have been inspired by the other.