I turned my nose up at Biggest Loser for years, but got drawn in during the stress of my husbands studying for the bar exam. The rates of weight loss are crazy, but I do think it demonstrates anyone can lose weight (like how anyone can cook from Ratatouille).
I dislike the reality TV politics, but Season 7 was a breath of fresh air. If you haven't seen season 7, I highly recommend it. Hulu has season 1 and then skips to 6. Once in a great while I might learn something, like why do dead lifts.