Saw the Horizon programme last year and have just finished the book.
I am a serial yoyo dieter, the most successful being with LighterLife in 2006 when I lost 6 stone. Unfortunately the gallstones I got from the diet nearly killed me (pancreatitis, liver damage)and over time the weight has gone back on and some more.
In January I went back to eating the way I did when I was younger and single - organic, vegan, high raw and this has helped me feel enornously better with a steady loss of 1-2 lb per week. I've done a lot of research and am eating really well with careful attention to my nutrition.
I am thnking of adding 5:2 to this way of eating to bump up the healing and weight loss so watch this space