A ketogenic diet is any diet that puts you into ketosis. The issue isn’t only what raises your ketone levels but also what lowers them. It is glucose that keeps you out of ketosis and that generally means restricting carbohydrates. But glucose can come from other sources. This is where protein come in. It has been a common view that too much protein would keep you out of ketosis. The theory was that gluconeogenesis, the process that turns proteins into glucose, could interfere with ketosis. So, some have worried that too much protein was basically no different than too many starches and sugar.
That view has been challenged by more recent research. The newer understanding is that gluconeogenesis is mostly demand-driven, not supply driven. That said, it’s more complicated than that. There are conditions that can alter demand or else signaling. Benjamin Bikman, an insulin researcher, advocates a higher protein ketogenic diet. He says that initially it might matter when someone first goes onto a ketogenic diet, if they have hyperglycemia and hyperinsulinemia, a problem for far too many Americans. But as insulin levels are normalized, which can happen quickly, gluconeogenesis is not a problem.
So, it depends on how healthy you are. With insulin resistance, high protein intake might spike insulin and cause the insulin glucagon/ratio to become imbalanced. Yet for a person with a healthy metabolism, the glucose/insulin ratio might not change at all. As Ben Wagenmaker explains it, “Studies do show that GNG affects obese people and diabetics, in that excess protein produces measurable spikes in blood glucose levels, although this same effect has not been observed and quantified in non-diabetics that are not obese” (Gluconeogenesis, Chocolate Cake, and the Straw Man Fallacy).
Considering that most Americans are obese, diabetic, pre-diabetic or insulin resistant, it might be advisable to limit protein until one has become fat-adapted and metabolically flexible. It’s easy to figure out for yourself, though. You can simply measure such things and see how it is affecting you. Or you can go by an even simpler method. Once your body is regularly in ketosis, fasting should become easy. If you can skip meals or go a day without eating at all and not be particularly bothered by it, then you know you’re body has fully adjusted to ketosis. At that point, protein should no longer be a concern.
This is good to keep in mind, considering most people turn to specific diets later in life. Bikman points out that, as people age, the body requires more protein for health. That is because the body becomes less effective at using protein. And if you don’t get enough protein on a keto diet, the body will cannibalize muscle. A lack of protein, in general, can be problematic — look at how lacking in musculature are many vegans with limited protein and lower quality protein. Muscle loss is a major health hazard for senior citizens, but muscle loss can begin much earlier in life.
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Dietary Protein and the Blood Glucose Concentration
by Frank Q. Nuttall & Mary C. Gannon
The relationship between gluconeogenic substrate supply and glucose production in humans
by F. Jahoor, E. J. Peters & R. R. Wolfe
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Protein, Gluconeogenesis, and Blood Sugar
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Ketosis Without Starvation: the human advantage
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The Ultimate Guide to the Carnivore Diet:
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the blood glucose, glucagon and insulin response to protein
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Protein Over-consumption in Ketogenic Diets Explained
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Keto Problems: Too Much Protein?
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