I dunno - I can't imagine anyone watching the biggest loser doesn't get the impression that it's exactly the sacrifice that she talks about. If she knows how to dehydrate herself to fool a scale, that's not going to do you any good for more than 1 weigh-in.
This is a competition - people want to win and they're going to get down and dirty to do it. Nobody thinks a lot of the sacrifices people make for the sake of competition are healthy, and usually you push yourself to unhealthy mental states to make them. I don't see why weight-loss has to be any different from any other type of competitive show on TV.
For me, nothing really surprising about what she said in there. IMO, the show doesn't perpetuate anything different from the rest of the mainstream world. At the very least, viewers of that show should realize that those people achieve those goals busting their ass, which at the end of the day is the remedy for a lot of people.
"Use what talents you possess: the woods would be very silent if no birds sang there except those that sang best." —Henry Van Dyke