Isnt that oil amazing?
When you say nasty, do you mean it lasts longer? Is it possible that the difference in how you felt was based on the type of carb (fruit juice versus muffin, thus fructose versus starch) rather than the fiber content? I can get away with eating a fair amount of fruit without ill effect; however, if I add in some starch I feel like total crap. Whenever I used spiked insulin post workout I would keep the fat and fiber to a min.