Here is one doctor's take on the Biggest Loser's methods

Is "The Biggest Loser" Risking Contestants' Lives? Dangerous Weight-Loss Techniques Revealed - Dr. Charles A. Evans, M.D., Ph.D-Dr. Charles A. Evans, M.D., Ph.D

And here is a Slate article about it
"The Biggest Loser" Exposes The Dieting Fraud

If you browse through all kinds of weight loss websites, you'll see that virtually all of them would say that weight loss should happen gradually, never rapidly. And any physician who is in the right mind would tell you that losing too much weight too fast is very dangerous to your health.

The Biggest Loser participants destroy their health in the hope to win a big sum of money. That's all this is about and this is very sad.