Scientists invent a pill for increased fat burn, how do you respond?

If:
Scientists finally figure out how to optimize metabolism and, with it, fat burn.
They do so with a prescribed pill, the dosage being dependent upon your body weight and current metabolism rate. Continued refills require regular checkups to monitor your weight and metabolism.

Then:
How would this affect your lifestyle choices?
Would you opt in to take this pill? Just a couple of times or regularly?
Would you opt your children in to take this pill?
What do you think of this concept as a regulated medical concept? Morally, scientifically, etc?

Keep in mind:
Links between certain diseases and obesity