I'd never heard of it till about a week ago, so I Searched for it
It looks to me that it's yet another variation on the 'lifestyle' - healthy living - self help' theme, with a bit of hi - tech gubbins thrown in
I expect it would work if you followed it, but you could do it yourself for much less money - £25 will easily buy you a set of bathroom scales, then 2 or 3 books for a few quid. Even cheaper if you go to your library, the health & diet sections usually have loads of them
And/or you can Surf & Search this and other forums & websites for free, as many as you have the stamina for
Most medical or community centres, and your GPs surgery will run, or have information about free or very cheap exercise & walking schemes. or join your local rambling club or branch of the Ramblers Association
I suppose what you're getting with this scheme is a more personal service and someone to nag you if you know you don't have much willpower or motivation