> - meal GI can be lowered by simply consuming more protein/fat based foods, or high grain foods alongside the food.

I'm not refuting your GI point but the combination of foods does have an impact on how they are digested. E.g. want to fatten a cow? Give it plenty of water with its food.

Other combinations such as wholemeal bread & fats are better than fats without wholemeal.

Denatured flour will re-absorb vitamins & minerals from the other foods on the plate.

I'm not advocating the Shang-ri-la but http://www.sethroberts.net/ has some good reading on the subject, particularly "What Makes Food Fattening? A Pavlovian Theory of Weight Control" - http://www.sethroberts.net/about/whatmakesfoodfattening.pdf