Reader Pete asked for some thoughts on the “Insulin Index,” a measurement chart similar to the glycemic index. While the glycemic index calculates the relative blood sugar rise induced by given foods, the insulin index evaluates the insulin response generated by 38 different foods.
The insulin index, which first made its appearance in a 1997 American Journal of Clinical Nutrition article, was primarily the creation of Susanne Holt, a graduate student at the time and now a doctor. Interestingly, Holt, her supervisory co-authors, or other researchers haven’t chosen to conduct further research to update the “preliminary” results of their insulin index study since its creation eleven years ago now.
While Holt and her co-authors found a high correlation between glycemic index and insulin index measurements, they stumbled upon an intriguing exception. High protein, virtually no-carb foods like meat and eggs, while low on the glycemic index, measured high on the insulin index. In other words, while the meat and eggs didn’t cause a spike in blood sugar the way most carbohydrates do, they did result in an unexpectedly significant rise in insulin. (Baked goods, with their high levels of refined carbs, elicited a very high rise in insulin as well. Of course, this comes as less of a surprise.)
Obviously, the index has some eyebrow-raising potential, especially in those of us who choose a high protein diet. But there’s more to the story here. First off, let’s remember that the protein-rich foods didn’t result in the physical stress of blood sugar spikes. But what about that rise in insulin? Why? Should I be concerned about that omelet I ate for breakfast?
Insulin, in and of itself, is a good and necessary thing. It promotes the storage of nutrients after all. In our natural, primal state, this was an essential process. Even in our modern lives, this storage process is still vital. (We just have a nasty habit of flooding the system these days.) In the case of high protein foods, it makes perfect sense that the body recognizes the need to store amino acids. (Primal life wasn’t a perfect set schedule of three square meals a day after all.)
The insulin helps drive amino acids into the muscle cells where they’re needed. At the heart of this process, one thing is for certain: the body knows what it’s doing.
But there’s another dimension to the protein-insulin issue. When we eat protein-rich food, another chemical is released by the body that actually has a contrary effect to insulin. Protein-rich foods also result in a release of glucagon. (Carb-rich food does not.) Glucagon raises blood sugar levels in part to allow for absorption of amino acids in the liver and their subsequent transformation there to glucose. In our evolution, we developed the capacity to make what we required out of what was available. If dinner was going to be part of a mammoth carcass, then the body could enjoy the protein it needed and use insulin response to store essential amino acids. Simultaneously, it had the glucagon to keep blood sugar stable in the absence of carb-based foods.
What does this tell us? It underscores the fact that we don’t need to (and shouldn’t) include extra carbohydrates in our diet. The carbs we get from vegetables and the glucose that can be made even from protein-based foods offer plenty of the right fuels our bodies need.
For people without diabetes, the insulin and glucagon responses mitigate each other, and we’re looking at a healthy picture. For people with diabetes or impaired insulin response, however, this picture is much different. In diabetics, this crucial equilibrium is damaged. The body not only has difficulty compensating for blood sugar spikes from carb intake, it’s also at a disadvantage when it comes to low-carb, protein-based meals with the lack of insulin-glucagon balance. (Another reason to avoid developing diabetes from the outset.) Nonetheless, diabetics fare better with a low-carb diet.
In short, while the insulin index raises some intriguing points, I don’t think it undermines the Primal Blueprint or unravels existence as we know it. It’s another bit of research that illuminates the natural interaction of our body’s systems with the diet we feed it. The index highlights the need for responsible food choices based on our inherent physiological functioning.