Actually white bread is highly processed wheat flour with almost all if not all of the bran/fiber removed therefore the body breaks in down into sugar much faster than whole grain breads thus causing far greater “sugar load” for the pancreas to deal with. It these sugar spikes that many experts now feel are the root cause of insulin resistance and all the myriad of disorders associated with it.
See metabolic syndrome.
Exactly, white bread is basically starch. Wheat bread is starch with the bran and germ remaining. But the germ and bran are only a small part of a wheat grain (guessing maybe 10 percent?), so the difference they make is small. Or at least that’s what I would expect, and my experience seems to bear this out. Both white and wheat bread eaten on an empty stomach can set me up for a sugar “crash”.
I think the benefit of whole grain breads is separate from the sugar issue. I think it’s mainly that compared to white bread they’re higher in fiber and nutrients. It’s kind of like fruit juices versus soft drinks. Fruit juices are much more nutritious but they’re still pretty hard on your pancreas.