Is there anything that can be added to a meal to lower the insulin index? Since fat lowers gastric emptying but actually increases the insulin response that is out. How about some insoluble fiber? Anyone know?
“The authors also note, as above, that some protein-rich foods induce as much insulin secretion as some carbohydrate-rich foods. Fibre was not found to predict the magnitude of insulin response.” - from the study by J.S.Coleman. I guess there is nothing much to be done about lowering II… 
Does that mean it’s okay to add a fiber source, such as psylium husk, to a post-workout shake? I’ve always avoided doing this for fear of reducing the desired insulin spike.
No. It simply means that fiber content in food is not in direct, let alone one-way connection with II. Nobody can predict II of concotion made of some, for example, GI MRP and fiber. It might be lower, but it also might be higher. If we’re talking about postworkout meal, I wouldn’t add any fiber or fat.
If slowing absorption of food achieves reduction of insulin index, you can take several capsules of glucomannan (root) with water before your meal. This root extract produces a thick, fibrous gel when it mixes with water. It can certainly reduce the glycemic index of a meal and make you feel full, so I feel confident it would have a similar effect on the insulin index. - Nylo
Insulin response to a meal is promoted via several mechanisms (and maybe others that we dont even know of yet).
1) Glucose appearance into the blood and interaction with pancreas 2) Amino acid appearance and conversion to glucose in the blood and interaction with pacreas 3) Amino acid interaction with pancreas 4) GI hormone response to specific food constituients.
So in trying to lower the GI of a given food, you have to know what causes the disproportionate insulin release. Then you will know whether an intervention to decrease II is possible. The problem is that in the particular foods of interest (milk, beef, etc) we dont know why there is such a big insulin release disproportionate to GI. If scenario #1 is the cause, then simply lowering GI with fiber may decrease II. If #2 is the case the same holds true (or you could just eat less protein). If #3 is the case then you cant do anything unless it's to not eat that food. And the same holds true for #4.
Nothing is ever simple is it?