Something crazy happens to you if you're chased by a tiger.
If you're not eaten, your body remembers the event. And if this type of event happens frequently enough, the body very quickly responds. For the best chances of survival in such situations, our bodies must be both light weight and have healthy, efficient muscle mass. The light weight allows for less effort and the dense muscle allows for power. Lightness and muscle = SPEED. And our bodies innately know that speed is what we need in danger like this, and it adapts accordingly, dropping fat and preserving lean muscle for survival.
So, to attain light weight with lean muscle, simulate the experience of being chased by a tiger!
It's about effort and heart rate. Short bursts (30-90 seconds) of intense "sprints" (running, cycling, burpees, etc), recover for 30-120 seconds, then repeat the cycle 5-10 times, and do that at least 4-7 times a week on a consistent basis. After you've adapted to a certain speed or level, you must continually increase the intensity as to not let your body get used to a certain level of effort. If you don't regularly increase the intensity when you've adapted to it, your body will think its weight and speed are exactly right, because you haven't gotten eaten by a tiger yet, and you don't seem to need to go faster or harder.
Start slowly if you're not sure what your safe max heart rate is, and continue to safely push yourself more and more as you increase lung/heart capacity.
For workout ideas to simulate a tiger chase, please email me through the "contact me" page.