Hiya,,,, slimfast isnt a very fast results diet obviously the more effort you put in the more you get from it,, results can vary from 2-4lbs roughly a week you normally have bigger losses when you first start but they slow down as your body changes and like all diets exercise is recommended to help these losses along.
Remember that the slower you lose it the more chance you have of it staying off lets be honest the weight didnt get put on in five minutes and isnt gonna come off in five minutes. Good luck with slimfast tho and i look forward to seeing you on the forum often.