The ketogenic, or keto, diet is characterized by low carbohydrate, high fat, and moderate protein intake, offering health benefits such as weight loss and improved blood sugar control. A key goal for individuals following the keto diet is achieving ketosis, a metabolic state where the body burns fat for fuel instead of glucose. Keto strips are often used to monitor ketone levels and determine if dietary adjustments are needed. This article explores how to use keto strips to measure ketosis, the different types available, their accuracy, and how to achieve ketosis through a ketogenic diet.
Understanding Ketosis
When following a standard high-carbohydrate diet, the body primarily uses glucose, derived from carbohydrates like sugars and starches, as its main energy source. However, when carbohydrate intake is restricted, as in a keto diet, the body seeks alternative fuel sources. This leads to the breakdown of stored fat into fatty acids and ketones. Ketones then replace glucose as the primary energy source, especially for the brain, resulting in dietary ketosis.
Being in dietary ketosis increases ketone levels, which can be detected in breath, urine, and blood.
Types of Keto Strips
There are primarily two types of keto strips: urine strips and blood strips. Each measures ketone levels differently and offers varying degrees of accuracy and convenience.
Urine Keto Strips
Urine strips are a convenient and affordable way to initially determine if you are in ketosis. These strips were originally developed for individuals with type 1 diabetes to assess the risk of diabetic ketoacidosis (DKA). They can be purchased over-the-counter at pharmacies, supermarkets, and online retailers.
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How to Use Urine Keto Strips
- Wash your hands.
- Collect a urine sample in a small, clean container.
- Immerse the absorbent end of the strip into the urine sample for a few seconds.
- Remove the strip and wait for the time specified on the packaging for the strip to change color.
- Compare the color of the strip to the color chart on the packaging to determine the concentration of ketones in your urine.
- Dispose of the urine and strip properly, then wash your hands again.
The color of the strip corresponds to the concentration of ketones in the urine, ranging from no ketones to high concentrations. A darker color indicates higher ketone levels.
It is recommended to test urine ketones at the same time each day, such as in the morning or a few hours after the last meal, for consistent comparison.
Limitations of Urine Keto Strips
Urine strips primarily measure acetoacetate (AcAc), a ketone body excreted in the urine. They are most useful during the initial weeks of starting a keto diet. During this period, the body is not yet efficient at using ketones for energy, leading to higher excretion of ketones in the urine.
However, as the body adapts to using ketones for fuel, it becomes more efficient at producing and utilizing them, leaving fewer unused ketones to be excreted. This means that after being in a keto-adapted state for several months, urine strips may show only trace amounts of ketones, potentially misleading individuals into thinking they are no longer in ketosis.
Urine tests measure ketones that have already been excreted, meaning they do not provide real-time data but rather indicate excess ketones produced previously. The accuracy of urine strips can also be affected by hydration levels. Dehydration can lead to more concentrated urine, potentially skewing the results.
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Despite these limitations, urine strips remain a useful tool for beginners to monitor the initial rise in ketone levels.
Blood Keto Strips
Blood ketone meters are a more accurate and reliable method for measuring ketone levels in the body. Originally designed for individuals with type 1 diabetes, they are also used by those following a ketogenic diet for more precise measurements.
How to Use Blood Keto Strips
- Wash your hands.
- Load the lancet with a new needle, following the directions provided.
- Insert a blood ketone strip into the ketone meter.
- Use the lancet to prick your finger and draw a small drop of blood.
- Allow the strip to come into contact with the drop of blood and wait for the results.
- Dispose of the strip and lancet as directed.
A desirable blood ketone level for dietary ketosis is between 0.5 and 3 mmol/L (9-54 mcg/dl).
Advantages of Blood Keto Strips
Blood ketone meters measure beta-hydroxybutyrate (BHB), the most abundant and stable ketone body in the blood. This provides a more accurate reflection of the body's current state of ketosis. Blood tests offer real-time data, which is particularly useful for those managing diabetes or fine-tuning their ketogenic diet.
Disadvantages of Blood Keto Strips
Blood strips are generally more expensive than urine strips, costing on average about $1 per strip. The need for a specialized meter and the ongoing cost of strips can make this method more costly. Additionally, blood testing is more invasive, requiring a finger prick for each measurement.
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Factors Affecting Ketone Levels
Several factors can influence ketone levels, including diet composition, individual metabolic differences, and activity levels.
Dietary Considerations
A keto diet typically consists of 65-90% of calories from fat, 10-30% from protein, and less than 5% from carbohydrates. Consuming too much protein can prevent the body from entering ketosis, as excess protein can be converted into glucose.
For comparison, the 2020-2025 Dietary Guidelines for Americans recommend:
- 20-35% of calories from fat
- 10-35% of calories from protein
- 45-65% of calories from carbohydrates
Generally, consuming less than 50 grams of carbohydrates per day is sufficient to induce ketosis, although individual needs may vary.
Time to Reach Ketosis
It typically takes several days on a keto diet to enter ketosis and a few more weeks to become fully keto-adapted. Urine strips can be particularly useful during this initial phase to ensure the diet is on track.
Ketone Testing for Specific Conditions
Diabetic Ketoacidosis (DKA)
Diabetic ketoacidosis (DKA) is a severe condition primarily affecting individuals with type 1 diabetes, although it can also occur in those with type 2 or gestational diabetes. DKA is characterized by absolute insulin deficiency, leading to increased lipolysis and the production of ketone bodies.
Patients with insulin-treated diabetes are often taught to monitor their glucose concentrations using handheld glucometers. Some meters advise testing for ketones if glucose levels exceed 13.9 mmol/l (250 mg/dl). Point-of-care ketone monitoring has been shown to prevent DKA and reduce unnecessary hospital admissions.
Euglycemic DKA
Recent reports have highlighted the risk of euglycemic DKA in individuals using sodium-glucose co-transporter 2 (SGLT-2) inhibitors. These drugs can improve glycemic control, but a subsequent reduction in insulin dose may increase the risk of DKA. Clinicians are urged to inform patients about this risk and the available testing options.
Monitoring Mild Ketosis
Monitoring mild ketosis can be useful for individuals adhering to severely energy-restricted diets. However, studies have shown that urine dipsticks are not accurate for detecting mild ketosis in non-diabetic populations. If monitoring mild ketosis is necessary, blood monitors are recommended instead.
Limitations of Ketone Testing
Both urine and blood ketone testing methods have limitations:
- Urine Ketone Sticks: These are inexpensive and easy to use but only provide a semi-quantitative measure of acetoacetate. They do not detect β-hydroxybutyrate, the predominant metabolite in DKA and can be affected by hydration levels.
- Blood Ketone Meters: While more accurate, blood ketone meters can be affected by factors such as abnormal hematocrit, changes in oxygen concentrations, and the presence of certain substances like vitamin C.
Interpreting Ketone Test Results
Ketone values vary depending on the test used. General guidelines for interpreting results are:
Urine Test Results:
- No ketones: Indicates that there are no detectable ketones in the urine.
- Trace amounts of ketones: May indicate that ketone levels are starting to build up.
- Moderate levels of ketones: Suggests a moderate level of ketosis.
- High amounts of ketones: Indicates a high level of ketosis, which may require medical attention.
Blood Test Results:
- Less than 0.6 mmol/L: Normal
- 0.6 to 1.5 mmol/L: Slightly high
- 1.6 to 2.9 mmol/L: Moderately high
- Higher than 3 mmol/L: Very high, indicating a risk of DKA
Managing High Ketone Levels
If ketone levels are elevated, it is important to take steps to bring them down:
- Drink extra water to flush out ketones.
- Test blood sugar levels every 3 to 4 hours.
- Avoid exercise if both blood sugar and ketone levels are high.
- Consume a carbohydrate-rich beverage like apple or orange juice to help lower ketone levels.
Lifestyle Changes to Maintain Safe Ketone Levels
- Maintain a consistent food and insulin routine.
- Understand how your insulin pump works and what to do in case of failure.
- Be prepared to test for ketones if you experience signs of DKA.
- Carry backup insulin in case of an emergency.
- Wear a medic alert ID to ensure quick and appropriate action in case of high ketone levels.