The exercises also get completed with a high intensity which makes the muscles grow and by reaching the anaerobic zone it helps burn fat. (bodyweight-workout.com)
Based on the theory of the fat burning zone, if you were to work out with a heart rate between 111 and 139 beats per minute, you would burn a higher percentage of fat during exercise than if you went above that number into the anaerobic zone. (coachcalorie.com)
I define it as the anaerobic zone, or at least 75 % max heart rate. (coachcalorie.com)