Physiological Insulin Resistance: The Hidden Adaptation Your Body Needs
If you've ever had a glucose test or checked your insulin levels on carnivore, you might have seen something weird: your fasting glucose is fine, but your insulin is elevated. Or your glucose tolerance test shows a sluggish response to sugar.
Your doctor might worry. You might worry. But this is actually normal. It's called physiological insulin resistance, and on carnivore, it's a sign your metabolism is working correctly.
What Is Physiological Insulin Resistance?
Insulin resistance sounds bad. It sounds broken. It's not. Physiological insulin resistance is your body's adaptation to a low-carb environment.
When you're in a low-carb state consistently, your muscles become insulin resistant by design. They're not taking up glucose because you're not giving them much glucose. Your body shuttles what little glucose you produce to your brain (the only organ that strictly needs glucose) and stores it. Everywhere else is running on fat.
This is adaptive. It's correct. It means your metabolism has shifted to using fat as its primary fuel.
Why This Is Different From Pathological Insulin Resistance
Pathological IR: You're eating carbs, your insulin spikes, your muscles don't take up glucose well despite high insulin. Blood sugar stays elevated. Inflammation increases. This is bad. This is the kind of insulin resistance we associate with metabolic dysfunction.
Physiological IR: You're eating carnivore (low carb), your muscles aren't taking up glucose because there's not much glucose around and they don't need it. Insulin is baseline but responsive. This is normal. This is adaptation.
The tests look similar, but the mechanism is totally different.
The Key Difference
On a mixed diet, high fasting insulin with high fasting glucose = bad. Pathological. Your body's having trouble managing blood sugar.
On carnivore, normal fasting glucose with slightly elevated fasting insulin = normal. Physiological. Your body is optimized for fat metabolism.
Why Carnivores Have This Adaptation
Your muscles spare glucose because there's not much glucose to spare. If your muscles are insulin-sensitive in a high-carb environment, they'll take up glucose greedily, which means blood sugar might drop dangerously low. Your body adapts by being slightly insulin-resistant to preserve blood glucose for your brain.
This is elegant. It's not broken. It's protective.
The Research
There's research on this from exercise scientists studying athletes doing very low-carb diets. The findings: yes, you can develop physiological insulin resistance on carnivore. No, it's not concerning. Yes, it goes away if you add carbs back. And yes, the metabolic markers that usually indicate problems (inflammation, triglycerides, LDL particle number) are usually excellent on carnivore despite the insulin resistance.
Which suggests the insulin resistance itself isn't the problem.
What Your Doctor Might Miss
A standard check might show elevated fasting insulin and minimal glucose tolerance. Your doctor might say "you're insulin resistant" and suggest you reduce fat or add carbs.
A more nuanced check would look at: inflammatory markers (C-reactive protein, IL-6), lipid profile, triglycerides, LDL particle number, glucose stability throughout the day, and metabolic markers. If those are good, the insulin resistance is physiological and protective, not pathological.
Ask For
If you're concerned, ask for a continuous glucose monitor for a week. See how your glucose actually behaves throughout the day. If it's stable between 70-100, you're fine. If it's bouncing around, something's off. The CGM is more informative than a single test.
One Important Caveat
This assumes you actually have good carbohydrate tolerance on carnivore. If you eat meat but also eat a bunch of processed food or carbs, you can have both pathological insulin resistance AND carnivore. Don't use "physiological IR on carnivore" as an excuse to eat cookies.
Will It Reverse If I Eat Carbs Again?
Yes. The adaptation reverses in weeks once you reintroduce carbs. Your muscles become insulin-sensitive again because they need to take up glucose for energy. This is why athletes doing carb-cycling don't have permanent insulin resistance changes.
Should You Worry?
No. Physiological insulin resistance on carnivore is normal. The markers that matter (inflammation, lipids, metabolic health) are usually excellent. If your doctor is concerned, get more detailed testing. But don't automatically assume elevated insulin on a low-carb diet means something's wrong. It usually means something's right.
The Research-Backed Take
Physiological insulin resistance is an adaptive response to consistent low-carb eating. It's not pathological. It's not metabolic dysfunction. It's your body efficiently managing the fuel source available. The confusion comes from the name sounding bad, but the mechanism is normal and actually protective.
If your metabolic markers are good and you feel good, you're fine. The insulin resistance is a feature, not a bug.
—Sarah