Comment by nkmnz

This is incorrect. Each minute of fast running bruns more fat than a minute of slower running. Longer slower running burns more fat only because you can do it for a longer period time, increasing total energy expenditure over the whole workout. If you want to maximize fat loss, you still need to maximize energy expenditure. If the available time is fixed and low, HIIT is the way to go. If the available time isn't fix or high relative to your capability to do HIIT, slowing the pace to fill the whole available time is the way to go.