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Insulin

Insulin is a hormone made by the pancreas that lowers blood sugar by moving glucose into cells for use or storage, while also signaling the body to store fat rather than burn it. When carbohydrate intake — and therefore insulin — stays low, that storage signal fades, which frees the body to release stored fat and make ketones. This is the hormonal switch that low-carb and keto diets are built around.1

What does insulin do in the body?​

Insulin is released by the pancreas whenever blood glucose rises, mainly after eating carbohydrate or protein. It acts like a key that unlocks cells so they can pull in glucose for immediate energy or store the extra as glycogen and fat. Insulin is fundamentally a "storage" hormone: high insulin tells the body to build up fuel reserves, while low insulin allows those reserves to be tapped.1

Why does low insulin matter on keto?​

Insulin suppresses lipolysis and ketogenesis, but neither pathway is a simple on/off switch. During fasting or carbohydrate restriction, lower insulin acts together with counter-regulatory hormones, fatty-acid delivery, and the liver's energy state to favor fat mobilization and ketone production. Gluconeogenesis is regulated glucose production from lactate, glycerol, and glucogenic amino acids, principally in the liver and renal cortex. Most fatty-acid carbon does not provide net glucose in humans; glycerol released from triglycerides can enter the pathway. The science of ketosis shows how these processes overlap.

Insulin resistance is a separate but connected concept: it describes cells that respond poorly to insulin, forcing the pancreas to release more of it to get the same effect. Chronically high insulin from insulin resistance keeps the body locked in "storage mode," making it harder to access fat stores — one reason carbohydrate restriction is often discussed as a strategy for improving insulin sensitivity. The glycemic index of a food is a rough guide to how much insulin it's likely to trigger.

Frequently Asked Questions

Does keto lower insulin levels?
Yes. Because carbohydrate is the strongest trigger for insulin release, restricting carbs on keto typically lowers both blood glucose and circulating insulin levels.
Can you be in ketosis with high insulin?
Not meaningfully. Insulin suppresses fat breakdown and ketone production, so consistently high insulin blocks ketosis regardless of carb intake.
Is insulin the same as insulin resistance?
No. Insulin is the hormone itself; insulin resistance is a condition where cells respond poorly to it, forcing the pancreas to produce more to compensate.
What triggers insulin release the most?
Carbohydrate raises insulin the most, protein raises it moderately, and dietary fat has little direct effect on insulin release.

See also​

Works cited​

  1. Ketogenic Diet — StatPearls, NCBI Bookshelf — August 18, 2026 https://www.ncbi.nlm.nih.gov/books/NBK499830/

Article history

  1. Corrected insulin, lipolysis, and gluconeogenesis physiology
  2. First published

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