Rather than trying to touch the bar to your chest or reaching your chin over the bar (both of which can produce dysfunctional mechanics), the goal should be to achieve proper upper back and lat activation. This requires several components.
Earlier this year, Dr. Lonnie Lowery wrote an article called 100 Workouts From Ripped City, which promoted light to moderate morning cardio for fat loss. It caused a stir amongst Testosterone contributors who'd been touting interval training as the supreme fat loss workout.