I'm a 100%-er too, although I must admit I don't feel that I need much will power.
Will power is not my strong point, but if I'm honest I've found abstaining from food MUCH easier than limiting it. It's easy to have a few extra fries, or another slice of toast etc. But when the rules are black and white, it's easy to stick to.
It also helps you recognise when you're really hungry and when you're not. I do get these hunger pangs and realise what they're triggered by now. Little things like adverts on the telly, or just watching a soap and the family are eating. If I was on a programme where I was allowed to eat, I would probably not even notice the trigger and just go and get something. Whether that something was healthy or not wouldn't matter - it was still calories I didn't need or genuinely want.
Being able to step away from food has given me an opportunity to examine my relationship with it. I haven't come to any conclusions yet (I've only done 2 weeks!) but already I feel positive I can lose this weight AND keep it off, and I can't wait for when I start eating again so that I can put all this into practice and prove to myself and others that I CAN DO IT!