Monitoring ketones: how do I know I am in ketosis?

Sue Heikkinen, MS, RDN, CDCES, BC-ADM, ACE-PT - Registered Dietitian Nutritionist and Certified Diabetes Care and Education Specialist

Thinking about monitoring ketones? You may choose to monitor blood, urine, or breath ketone levels to evaluate response to your keto diet and to provide extra motivation.

Should I be monitoring ketones?

You have been working hard to limit carbohydrates. But how do you know you are in a state of ketosis?*

Ketone monitoring gives you confirmation that your diet plan is working. Ketones are formed when fat is burned as an energy source when carbohydrate is not present. Of course, this is the goal of a keto diet. Ketone monitoring can be motivating to help you adjust your plan to reach your goal. Ketone monitoring is especially important if you are using a keto diet for medical purposes, such as the management of epilepsy.

Cost and inconvenience may be reasons not to use a ketone monitor. Also, you might find ketone monitoring unnecessary if your weight loss is already telling you the plan is working.

If you choose to monitor ketones, you can choose blood, breath, or urine testing. All methods of ketone monitoring will give you results in seconds. There are benefits and limitations to each method.

*Note: this article does not address ketoacidosis, a serious condition that can occur in people with Type 1 diabetes.

Methods of monitoring ketones

Blood

How it works:

Blood ketone levels are the gold standard of ketone monitoring. Blood ketone meters use a small drop of blood (from a fingerstick) placed on a test strip, which is inserted into the meter. A result appears in seconds.

Ketone measured:

Beta-hydroxybutyrate, in mmol/L

Ranges:

Light Ketosis: 0.5-1 mmol/L
Optimal Ketosis: 1.0-3.0 mmol/L

Pros:

• Measures ketones in real-time
• Number result
• Reliable
• Results can be saved
• Many meters also give blood sugar values

Cons:

• Invasive
• Cost
• Battery/power source required

Breath

How it works:

Squeamish about blood or urine testing? Monitoring breath ketone levels might be for you. Breath ketones measure acetone, a ketone small enough to pass from blood through the lungs. Breathe deeply into the handheld monitor, and the result appears in seconds.

Ketone measured:

acetone in parts per million (ppm)

Ranges:

Ideal levels are often considered 5-30 ppm, though levels may be as high as 75 ppm for those on a keto diet.

Pros:

• Non-invasive
• Number result
• Reliable
• Results can be saved

Cons:

• Cost
• Battery/power source required
• Breath alcohol can be confused with ketones

Urine

How it works:

Monitoring urine ketone levels is the original method of home ketone monitoring. A test strip is dipped in urine. The color on the strip reflects the urine ketone level. Match the strip color to the color on the chart to find the level of ketones in the urine.

Ketone measured:

acetoacetate

Ranges:

Negative = 0, Trace = 1, Small = 2, Moderate = 3, Large = 4, Very large = 5

Pros:

• Inexpensive, simple
• Non-invasive
• No power source needed
• Portable

Cons:

• Less accurate; may not show ketosis as your body adapts to keto diet
• Delayed result; does not show current ketone level
• Hydration can affect the reading. Dilute urine can appear as weak ketones, while concentrated urine can appear as strong
• Uses a color chart, no specific number

Monitoring Ketones with MyNetDiary

MyNetDiary Premium makes it easy for you to stay on track with your keto plan by allowing you to record your ketone levels, no matter which method you use. You can also chart your ketone levels over time.

Still new to MyNetDiary? Learn more today by downloading the app for FREE.

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