I did that all last week (broke 3 into superspeed soup, plus ate another 2 withs cheese spread every day) and only lost 1/2lb and didnt notice anything different re bathroom habits.
Seems it doesnt have the effect on all of us
There are 2 types by the way - scan bran and oat bran. Cant say i prefer one type over another, I've tried both, but tend to stick to the original (scan bran in the blue packet)
