One of the most confusing things people experience when they start paying attention to their blood sugar is this:
“Why is my glucose going up when I didn’t even eat carbs?”
It feels unfair. You skip the bread, the pasta, the sugar… you eat protein or fat instead… and your glucose still rises. Cue frustration, self-blame, and a lot of bad nutrition advice floating around the internet.
So let’s slow this down and actually talk about what’s happening inside the body, because it’s not random.
Your body is incredibly smart. When you eat protein, your body breaks it down into amino acids. Those amino acids don’t just float around aimlessly. If your body senses that there isn’t enough incoming glucose, especially on a low-carb or keto-style diet, it activates a backup system called gluconeogenesis, which literally means “making new sugar.”
In plain language:
Your body can turn protein (and parts of fat) into glucose.
This process is largely driven by a hormone called glucagon. Glucagon is insulin’s counterbalance. When blood sugar drops, between meals, overnight, or when carbs are very low, glucagon tells the liver, “Hey, we need fuel.” The liver responds by converting amino acids into glucose and releasing it into the bloodstream.
Once that newly made glucose shows up, insulin has to be released. Not because something went wrong, but because insulin’s job is to move glucose into cells so it can actually be used.
This is where people get tripped up.
They see insulin after protein and think, “Protein spikes insulin just like sugar!”
But that’s not the full story.
Insulin doesn’t just manage blood sugar. It’s also a growth and repair hormone. After protein intake, insulin helps shuttle amino acids into muscle tissue and turns on protein synthesis. In other words, insulin is required if you want to build or maintain muscle. That’s not a flaw, it’s biology.
Now let’s talk about fat, because this part really messes with people.
Fat doesn’t turn directly into glucose the way carbs do, but it still triggers insulin. One reason is a gut hormone called GIP (gastric inhibitory polypeptide). When fat hits the intestine, GIP signals the pancreas to release insulin in anticipation of incoming energy. This is part of the normal digestive response.
But fat has another effect that’s far more important long-term.
High levels of dietary fat, especially circulating free fatty acids, can interfere with insulin signaling at the cellular level. That means insulin is present, but cells don’t respond well to it. Glucose can’t enter the cell efficiently, so it stays in the bloodstream longer.
This is insulin resistance.
So even if fat doesn’t cause a dramatic glucose spike the way sugar does, it can quietly sabotage how glucose is handled afterward. The result? Higher blood sugar despite low carb intake.
This is why some people on very low-carb, high-fat diets are shocked to see elevated fasting glucose or stubborn post-meal numbers. Their body isn’t “burning sugar wrong,” it’s adapting to a fuel environment that constantly signals scarcity of carbohydrates and abundance of fat.
Early in ketogenic or very low-carb diets, gluconeogenesis ramps up hard. The body hasn’t fully shifted into ketosis yet, so it relies heavily on protein and fat to keep glucose available for tissues that still need it (like red blood cells and parts of the brain).
Again, this is not a mistake. It’s survival physiology.
The bigger takeaway here isn’t “protein is bad” or “fat is bad.”
It’s this:
👉 The body will always prioritize stable blood glucose.
👉 Insulin isn’t the enemy, it’s the messenger.
👉 Chronic insulin resistance is more about excess fat exposure than occasional glucose.
If you’ve ever felt like you were “doing everything right” and your numbers still didn’t make sense, this is why context matters. Metabolism is dynamic. Hormones respond to patterns, not just individual meals.
Understanding that can be the difference between fighting your body… and finally working with it.
If this clarified something you’ve been struggling to understand, save it. Re-read it. And most importantly, be gentle with yourself. Your body is adaptive.
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