I haven't done slimming world, but did look into it at one point.
WW is done by the theory that nothing is off limits in your diet as long as a) you use some portion control and b) you count it. YOu have a set number of points in a day, and every food has a point value. As long as you don't exceed your points, you will lose about 1-2 lbs per week.
Slimming world is a bit different. Apparently you have different days where certain foods are good or bad. ON a red day, for example, you can eat lots of startches and certain meats, on another day, it's all veggies, fruit and meat. On a red day, sweets would be "sins" and you have a set amount of sins you can have each day. That's probably not quite right, but from what I've read in the magazine, that's how it works generally.
Slimming World seemed a bit too complicated to me, which is why I went by way of WW, which I have been doing for almost a year now (gasp!)
