Ketones without the mystery: what they are, where they come from, and why you don't need to chase them
The word “ketosis” sounds like a diagnosis, and half the fears surrounding low-carbohydrate eating come from it. The truth is simpler: ketones are fuel that the liver makes from fat when carbohydrates are scarce, and the brain runs on them no worse than on glucose. This is the state of every person after a night's sleep and every breastfed baby. Section — metabolic flexibility.
Where they come from and why
The brain cannot burn fat directly — fat molecules cannot pass through its barrier. When glucose is scarce, the liver breaks fat down into ketones — small water-soluble molecules that can pass through. According to the data, the brain works more steadily on ketones: without post-meal crashes, and this is one of the reasons for a “clear head” with the method. Muscles and the heart burn both fat and ketones. This is a backup system built into everyone — otherwise humanity would not have survived a single winter.
Ketosis versus ketoacidosis
| Nutritional ketosis | Diabetic ketoacidosis |
|---|---|
| Blood ketones | 0,5-3 mmol/L |
| Insulin | low, but present |
| Blood sugar | normal |
| Blood pH | normal |
| Who | anyone without carbohydrates, after sleep, while fasting |
| Danger | none |
0,5-3
mmol/L — nutritional ketosis
×10
difference from ketoacidosis
every morning
mild ketosis in everyone
not necessary
measure
To measure or not
Blood — accurate, using a glucose meter with ketone strips; breath — devices that detect acetone, convenient; urine — strips that show only the first few weeks and depend on water intake. But the method isn't about the ketone number: hunger between meals has gone, energy is steady, the 16/8 window passes unnoticed — the switch has happened, and that's the only thing that matters. Chasing 3 mmol/L leads to “fat bombs,” spoonfuls of oil, and excess calories. Ketones are a thermometer, not a goal. The full picture of metabolic flexibility.
Mistakes
- Eating fat for ketones — “fat bombs,” spoonfuls of oil in coffee
- Getting upset about 0,3 instead of 1,5 — with steady well-being, it doesn't matter
- Confusing ketosis with ketoacidosis and being afraid
- Thinking keto flu is “ketone poisoning” — it's salt and water
- Testing urine after a month — it no longer shows anything
Frequently asked questions
Is ketosis required for the method?
No. The method is low-carbohydrate eating with pauses; mild ketosis occurs on its own, but it isn't the goal. Vegetables and berries on the plate are normal.
Acetone breath?
During the first weeks, some ketones leave through the breath. Water 2-3 L, salt, and it passes within 2-3 weeks as you adapt.
Ketones and the kidneys?
In healthy people, nutritional ketosis is safe for the kidneys. With kidney disease and type 1 diabetes — only with a doctor.
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Reviewed by Anastasia Zhukova, Fitness Trainer • Author of a Nutrition and Training System • Creator of an AI Personal Support Platform
A human has reviewed this material against the method and real client practice.