Any advice: My stomach seems to be liking me less & less, whenever I run for more than 40 minutes my food seems to want to evacuate (to put it nicely). I originally thought that it was a problem with corn, but have cut that out, then it was oats. I thought I'd done everything right on Saturday before a half-marathon on Sunday but again had to jump into some bushes after 9 miles & I'd taken some Immodium. I am assuming its foods that are too fibrous, any ideas on how to remedy this? I am running the London Marathon & don't want to be stopping every mile, especially as it often means I have a poorly stomach for a couple of days after.