hey i heard HIIT cardio is the only way to go with fat loss because regular intensisty just raises cortisol which results in a loss of Lean body mass..i find 15 min of HIIT easier but harder-than jogging for 45 min..and is walkin on a hil; for 45 min catobolic or a waste of time for fat loss..i do that on the days i dont do HIIT sprints.