I can't believe no one answered this for you yet. But if you do the following:
Body.GravityScale = -1.0f;
You simply give the body of the player a negative gravity by multiplying it with a scale of -1.0f. If your player consists out of multiple bodies like mine, you change all of their gravity scales to -1.0f. Learned something new myself, haha.
Hope this helps and I wasn't too late.