Ketogenic diet and why ketone monitoring changes the game
The ketogenic diet (keto) has evolved from a niche diet to one of the most popular nutritional protocols in the world. In my medical practice, I see more and more patients - not just those with diabetes, but also healthy individuals who want to optimize their metabolism - adopting a low-carb or ketogenic eating style.
The principle of the keto diet is simple: by drastically reducing carbohydrates (below 20-50 g per day), the body switches from burning glucose to burning fat as the primary energy source. The liver transforms fatty acids into molecules called ketones (ketone bodies), which fuel the brain, muscles, and organs. This metabolic state is called ketosis.
But the question that concerns me as a physician is: how do you know if you're truly in ketosis? And more importantly: how do you stay in optimal ketosis without guessing?
What are ketones and why their levels matter
Ketones (ketone bodies) are three distinct molecules produced by the liver in the process of beta-oxidation of fatty acids:
- Beta-hydroxybutyrate (BHB) - the most abundant ketone in blood (~78% of total ketones). It is the reference biomarker for measuring ketosis and the only one that can be measured accurately through a continuous sensor.
- Acetoacetate (AcAc) - the second most abundant ketone, measurable in urine through test strips.
- Acetone - a volatile ketone, measurable in exhaled air. Causes characteristic "keto breath."
The level of BHB in blood is considered the most accurate and relevant indicator of ketosis:
- Below 0.5 mmol/L - you are not in ketosis (the body burns predominantly glucose)
- 0.5 - 1.0 mmol/L - light ketosis (fat burning begins, but not optimal)
- 1.0 - 3.0 mmol/L - optimal ketosis (ideal zone for keto diet benefits)
- 3.0 - 5.0 mmol/L - deep ketosis (acceptable in non-diabetic context, but requires monitoring)
- Above 5.0 mmol/L - potentially dangerous, especially for people with diabetes (risk of diabetic ketoacidosis)
Important medical note: Nutritional ketosis (BHB 0.5-3.0 mmol/L) is fundamentally different from diabetic ketoacidosis (BHB >3.0 mmol/L + very high blood glucose + acidosis). Diabetic ketoacidosis is a medical emergency. Nutritional ketosis is a physiological metabolic state.
Classical methods of measuring ketones - their limitations
Until recently, those who wanted to monitor their ketones had three options, each with significant limitations:
1. Urine strips (acetoacetate test)
- Price: ~0.5-1 RON per test
- Advantages: Cheap, non-invasive, available in pharmacies
- Major disadvantages: Measures acetoacetate (not BHB - the most relevant), results are strongly influenced by hydration (dilute urine = false-low result), become less reliable as the body adapts to ketosis (keto adaptation reduces acetoacetate in urine even if blood BHB is high)
- Verdict: Useful only in the first few weeks of keto, then become unreliable
2. Glucometers with ketone function (blood BHB test)
- Price: ~5-10 RON per test (ketone strips are expensive)
- Advantages: Accurate (measures blood BHB), reference standard
- Disadvantages: Requires finger prick with each measurement, test costs add up quickly (at 2-3 tests/day: 300-900 RON/month!), provides only a single point value without trends or graphs
- Verdict: Accurate but expensive and inconvenient for regular monitoring
3. Breath analyzers (acetone test)
- Price: 200-500 RON device, no recurring costs
- Advantages: Non-invasive, no per-test costs
- Disadvantages: Limited accuracy, influenced by hydration and breathing, does not measure BHB (the reference biomarker), inconsistent correlation with actual ketosis
- Verdict: The least reliable of the three methods
SiBio KS1 - The first continuous ketone monitoring sensor
SiBio KS1 from SiBio represents a truly revolutionary innovation: it is the first continuous ketone monitoring sensor (CKM - Continuous Ketone Monitoring) available on the market. It works on the same principle as a CGM sensor, but instead of glucose, it measures beta-hydroxybutyrate (BHB) in interstitial fluid.
How SiBio KS1 works
The sensor is applied to the skin (usually on the back of the arm), just like a CGM sensor. A thin filament under the skin continuously measures BHB levels, transmitting data via Bluetooth to the SiBio app on your smartphone. In the app you see:
- Real-time ketone levels - you know at any moment if you're in ketosis
- Ketosis graph over hours and days - you see complete fluctuations, including at night
- Correlations with food - you identify exactly which foods keep you in ketosis and which take you out
- Impact of exercise - you see how different types of training affect your ketones
- Customizable alerts - you're notified when you exit the optimal ketosis zone or when levels rise too much
This is a fundamental difference from classical methods: instead of a single point measurement, you get a continuous film of your ketosis. It's like the difference between taking one blood glucose photo per day (glucometer) versus having a continuous film (CGM) - the same revolution, but for ketones.
Why continuous ketone monitoring changes everything for the keto diet
From clinical experience and feedback from my patients, here are the most valuable benefits:
- Elimination of guessing - you no longer have to assume you're in ketosis. You know for certain, at any moment.
- Optimization of carbohydrate threshold - each person has a different carbohydrate threshold at which they exit ketosis. With SiBio KS1 you can identify exactly this threshold and build your diet around it.
- Understanding ketosis timeline - how long does it take to enter ketosis after a carb-containing meal? How quickly do you exit? With continuous monitoring, you get precise answers.
- Nighttime monitoring - nighttime ketosis is often the most stable. With SiBio KS1 you confirm this and can adjust your dinner accordingly.
- Safety for diabetics - people with diabetes following a keto diet have an increased risk of diabetic ketoacidosis. Continuous monitoring with alerts significantly reduces this risk.
The ideal combination: SiBio KS1 + CGM Sensor
For a truly complete metabolic picture, the combination of SiBio KS1 (ketones) with a CGM sensor (blood glucose) is extraordinarily powerful. You see simultaneously:
- How blood glucose drops when ketones rise (entering ketosis)
- The exact impact of each meal on both parameters
- The correlation between exercise, blood glucose, and ketones
- The complete metabolic picture, 24/7, without finger pricks
CGM sensors available on PrimeMedical.ro that can be combined with SiBio KS1:
- LinX CGM - the smallest and most accessible, IP68
- Sibionics GS1 - maximum accuracy (MARD 8.83%)
- Sibionics GS3 - the thinnest (2.9 mm), maximum comfort
Who is SiBio KS1 recommended for?
- Keto diet enthusiasts - who want to confirm and optimize ketosis objectively, not based on subjective sensations
- Athletes and biohackers - who experiment with low-carb nutrition protocols, intermittent fasting, or extended fasting and want precise data
- People with diabetes following keto - continuous monitoring reduces the risk of diabetic ketoacidosis and provides additional safety
- Nutritionists and dietitians - who want to provide clients with objective data about the effectiveness of prescribed dietary protocols
- People in therapeutic fasting - monitoring ketones during extended fasting provides safety and valuable information
Practical tips for using SiBio KS1
- First 3 days: Don't modify your diet - just observe. See what your baseline level is.
- Experiment in a controlled way: Change one thing at a time (for example, add 10 g carbs at dinner) and monitor the impact on ketones.
- Keep track of what you eat: Correlate SiBio KS1 data with a food journal. You'll quickly identify foods that affect your ketosis.
- Monitor exercise: Intense exercise can temporarily lower ketones (muscles consume them). Don't be alarmed - it's normal.
- Set alerts: Configure minimum ketosis alert (0.5 mmol/L) and maximum (3.0 mmol/L) to stay in the optimal zone.
Final tips
SiBio KS1 represents the same type of revolution for ketone monitoring that CGM sensors brought to blood glucose monitoring: the shift from point measurements that are inconvenient and imprecise to continuous, automatic, real-time monitoring.
If you follow a keto diet or any low-carb protocol, SiBio KS1 will allow you to move from assumptions to concrete data. Combined with a CGM sensor, you get a complete metabolic picture that was previously available only in research laboratories.
The sensor is available on PrimeMedical.ro with fast delivery throughout Romania. For questions or personalized recommendations, we await you on the contact page.
Also read: Glucometer vs CGM Sensor | Top 5 CGM sensors Romania 2026 | Complete CGM sensors guide
