I've been doing a consistant 30 min of cardio every morning on an empty stomach at 60-75% my max heart rate...blah blah blah (all standerd stuff)

Yesterday im reading on bodybuilding.com how that it is now thought to not be the best from; that I should be doing 15-20 min HIIT (at 15 seconds all out sprint (95% max), 45 seconds slow jog (50% max)) in the morning AFTER eating a high protien meal. It also said that this was the better way for muscle retention.

so which one is best for mucsle rentention????? (and obviously fat loss)

thanks
-Capone