If you are already performing HIIT, I would suggest bumping the intensity up to around 90-95%.
I prefer performing HIIT intervals with a lower duration (e.g. I find it hard to believe that most people are able to perform sprints at 90-100% intensity for over a minute (let alone repeat this several more times), which is why I stick to a lower duration and push hard throughout the work intervals.
You can do HIIT with weights, swimming, boxing, jump rope, and the list goes on.
But not all forms of HIIT are equally beneficial when the goal is to get to 10% body fat while maintaining as much muscle mass as possible.
However, the leaner you get the more often you will have to overload your HIIT workouts in order to get rid of stubborn areas of fat like the lower abdominal region.