In the first three episodes (of eight total to come in season one), highly likeable trainer Chris Powell (who is a Bob Harper-style trainer), worked to successfully transform three different "super obese" people--those who have more than 200 pounds to lose, Sounds like Biggest Loser, but how is it different?
Extreme Makeover: Weight Loss Edition doesn't have competition between participants, and takes a longer-term view. Each episode focuses on just one individual's weight loss journey over the course of a year.
Chris Powell starts each episode with a bootcamp and immersion in healthy lifestyle tactics for a week at a California health institute, and then moves in with the story subject for the first three months to make sure that healthy habits take hold. This explains why there are only eight episodes of the show, but it has already been picked up for a second season, where I imagine Chris will have to move in for a shorter period of time to make the show work--maybe more like a week like Jillian Michaels did in Losing' It With Jillian (which I wish had another season).