I think the problem is that insulin and glycemic index may or may not be very accurate. It also depends on how much you eat. The more you eat the bigger the spike you get. It also isn't JUST insulin, it's the sugar that certain foods break down into as well. I would think the glycemic score would matter more, since insulin does more than just metabolize sugar. You can't really equate what insulin does with one substance, to what it does with ALL substances. Especially since the concepts we are discussing are in reference to metabolizing sugars.
You also seem to be under the impression that if you can show medical science does not know every single tiny detail having to do with this, that the whole thing is wrong, and you are right. That just doesn't logically follow. It just shows that we don't know everything, which is a given anyway.
that you can eat a low-calorie diet and still gain weight if you're eating the "wrong" foods (insulin sabotaging your weight loss, total reduced calories putting you into "starvation mode" and reducing metabolism), and that if you just eat the "right foods" you can eat to your hearts content.
Some people with a simplistic understanding may say something like that, but just because SOME people say that doesn't mean we all agree. In fact if you notice my position is different than that. So you seem to be applying someone else simplified view, to be my position, so you can then effectively argue against it.
Now if you are just saying that some people say that, and it's overly simplistic and not completely accurate, I won't argue about that.