Sorry guys - I have heard all sorts of CRAP about diets (usually during the more boring parts of long-haul flights), and people are all too ready believe all sorts of duff gen if they like what they're hearing - but there are two ways to lose weight and two ways only;
1 - eat less
2 - do more.
That is it. In fact that is ALL of it.
You can carry on all you like about what makes up the diet (and that may be important if you have various medical conditions), however the bottom line is that if you want to lose weight you must eat less or do more! The only proviso is that the diet must be reasonably balanced (and most people's are - don't get me started on vitamin supplementation).
Here endeth the lesson.
(BTW In addition to my ATPL I also have post-graduate education in nutrition)