The UK reality show "I'm a celebrity... Get me out of here!" (see link) might not be to everyone's liking, but one thing's for sure - it's a great aid to weight-loss.
Contestants can lose something like 2 stones whilst in the jungle (approx. 2 weeks), and I think this is pretty impressive.
a similar facility for non-celebrities, but sans Antandec and TV coverage.
Each 'contestant' is subjected to thorough psychological profiling, and is only grouped with other compatible 'contestants' in order to keep conflict to a minimum.
Meals are earned in the same way as in the show - 'Bush tucker trials'. Thankfully, none of these trials are of the icky insect-eating variety - trials are either mental or physical challenges.
Not only would the 'contestants' leave the jungle slimmer, they would hopefully also learn something about themselves and their decadent, consumerist lifestyles.