First, let’s discuss WHY whey is insulogenic. It’s insulogenic because it is VERY fast digesting and absorbing as a form of protein. That’s why it’s ideal for peri-workout nutrition. It ensures that amino acid substrate is available at the time that it is most needed by the body. That it is insulogenic means it has raised BG. However, a rise in BG, as well as a rise in insulin does not necessarily prevent ketosis. It may lower it somewhat, as there is some evidence that the presence of insulin requires a substantial glucagon response to remain ketogenic…to that point, the Bisschop study indicates that for a ketogenic individual, the glucagon increase is commiserate with the insulin spike (something that wasn’t observed in the non-ketogenic dieter) meaning the I/G ratio is preserved when protein consumption happens.