I think most of us with IBS are on some sort of restricted diet, and I do know that some foods (especially some fruits) give me diarrhoea. But, most of the time I eat pretty much the same thing every day, and one day I will be constipated and the next I will be rushing to the loo. Sometimes I can put this down to being stressed - but not always.
There must be something else going on that is making the bowels function in such an erratic and random way