Hi, I started this method (not really a diet) after Xmas when I hit 17 stone and felt incredibly lethargic and tired and so far it's helped a lot. He suggests four easy rules that make sense to me, anyway.
If you are hungry (really) go and eat.
Eat what you like (really, really even chips or chocolate)
Eat really slowly, savouring every mouthful (out your fork down after each bite, no eating in front of TV either)
Then, when you are full, or even think you are full, STOP. You have to learn when you are full, and eat slowly enough for your stomach to let you know when you can stop eating.
This way, you eat a healthy range of foods and just less of them. My size 10 22 year old daughter eats naturally like this so I follow her. So far, 2 and a half stone gone and no rebounding if I take a week or two off.
I found if I gave myself a really small portion but told myself I can always have more, or put some in the microwave in case I get hungry later, it helps. Like a lot of chronic over-eaters, I didn't know when I was full at first so I would stop eating the second I thought I might be, then let my food congeal on the plate. I gave myself permission to throw food away, even in a restaurant or at family dinners.
He suggests you DON'T weigh yourself more than once every few weeks, don't eat diet foods (thin people don't) and get a pedometer to gradually incraese your activity levels. I put my 4000 steps a day up to 6000-10000 a day, my blood pressure came down, my diabetes improved as well. The book (with CD) is in the shops or the rules are on his website. I have dieted for 25 years, getting fatter after each one, and have never lost weight so slowly and felt so well while I was doing it. I don't even feel deprived!
I know this sounds like a sell, but compared to Weightwatchers etc. it is a really commonsense and free approach. He did a series for American TV too, it's repeated occasionally on satellite. Worth a try, and definitely not a gimmick.