When discussing resistant starch, there are various forms. Bananas have the form RS2, which has been shown to improve insulin sensitivity in several studies. Whole grains usually contain the resistant starch RS1 or, if well cooked/prepared, RS3. RS1 is mostly indigestible and RS3 appears hard to digest. RS1 RS2 appears quite beneficial, and the others (especially RS1) don't.

Also, I think people typically say the problem with grain fiber is the insoluble fiber. Chris Kresser recently covered this and many issues fiber related: http://chriskresser.com/myths-and-truths-about-fiber

When discussing resistant starch, there are various forms. Bananas have the form RS2, which has been shown to improve insulin sensitivity in several studies. Whole grains usually contain the resistant starch RS1 or, if well cooked/prepared, RS3. RS1 is mostly indigestible and RS3 appears hard to digest. RS1 appears quite beneficial, and the others (especially RS1) don't.

Also, I think people typically say the problem with grain fiber is the insoluble fiber. Chris Kresser recently covered this and many issues fiber related: http://chriskresser.com/myths-and-truths-about-fiber