I'm really surprised at how hard they push them physically
- but I suppose they have complete physicals before they start the program and probably sign a waiver...

If you are locked away from everything and not much to do but exercise and eat only certain foods - it's a given that you would lose a lot plus the extra embarrassment if you don't and it being on TV and all.

Real life can't really compare to it - but use it as an incentive to aim for keeping as active as you can and keeping junk food out of the house etc..