The NY Times article about the Biggest Loser contestants has been showing up in various places I follow. I've only skimmed it, but my preliminary reaction is "I'm surprised anyone's surprised." Which I know sounds dismissive, and I know it's annoying when people say that. But time and time again it's been shown that starvation diets don't work long-term.
It's old news that your metabolism slows down when you starve yourself. That's partly why simple calorie restriction doesn't work. That approach might be fine if calories-in and calories-out were independent variables, but they are not: reducing the former affects the latter. If you simply starve yourself using blind calorie counting, your body will change its energy budget, and now you're chasing a moving target, on top of which you feel crappy.
Another fallacy in "calories in, calories out" is that most people take that to mean calories in and out of the body as a whole. But what we care about is calories in and out of our FAT CELLS specifically, and that simple change in perspective leads to useful ways of reasoning.
We KNOW that WHAT you eat — as in protein vs. fat vs. carbohydrate — has a large effect on how your body meets its energy budget, in particular, how much energy it gets by burning fat. We KNOW that carbohydrates bump insulin, and insulin is the primary driver that tells fat cells to get fatter and more numerous. None of this comes from some recent magic discovery. It's old, boring, first-year-med-school news . But I can't tell from the article how much of this knowledge was applied to the Biggest Loser contestants.
By the way, it also seems there is a lot of variation among individuals in how they respond to a given intervention, which to its credit the article does mention.
The findings about levels of leptin and other satiety hormones are interesting. My current understanding is that we still have a lot to learn about the hunger and satiety hormones, but they're a promising avenue of research. My understanding is that fat cells secrete leptin, which means it should be no surprise that huge decreases in fat caused the subjects' leptin levels to drop precipitously. I've seen a claim  that insulin blocks leptin from getting its message to the brain. But I hesitate to make any strong claims about hunger and satiety hormones — the research is much more recent than what we know about insulin.
My impression is that the Biggest Loser show took an approach to weight loss that has been proven to fail, and dialed it up to 11 for entertainment value. That's my impression, but I'm open to learning that I'm wrong. And if useful science can result regardless of that, then at least that's a good thing.
 At least that's what I've read. I'd be curious if any of you who are doctors or know doctors can confirm. One of the books I have shows a chart from a med school textbook that supposedly supports the "first-year med school" claim. I'll try to find it. But whether or not it's strictly true that any rookie med student "knows" this about insulin, I'm pretty sure it's long-established fact.
 The Skinny on Obesity (Ep. 3): Hunger and Hormones- A Vicious Cycle
My caveat on this video is that Lustig has been criticized for his claims about fructose. I'm not sure yet how to evaluate the criticisms. But what he says about insulin jibes with everything I've read. Again, I'm open to learning that I'm wrong.