Is testing necessary while on a ketogenic diet?

It depends on your goals and whether you’re the type of person who is data driven. If you’re using the ketogenic diet as a mean to lose weight and you’re not seeing any changes after 3-4 weeks. It may be a good idea to test and see if you’re in nutritional ketosis.

While there’s no universal standard guidelines to what one needs to achieve when testing. Blood ketones between 0.5-2 mmol/L seems to be accepted as the nutritional ketosis state.

Some of you may like to measure the ketones as a way to keep yourself on track and serves as a motivation. This is quite reasonable. In my opinion, once you’ve worked out what food keeps you on nutritional ketosis, you can probably ease off the tracking. But if you start a new training program or new food, you may choose to measure it again. This may serve as a learning tool more for yourself as you learn about the impact of the new interventions.

Is there a best time to test for ketones?

Initially you might test yourself before your breakfast or first meal. Typically you should detect some ketones upon rising, assuming that your last meal was at least ten hours post waking, you have essentially done a “prolonged overnight fast”. There might be some reasons as to why you are not detecting any or low ketones:

  1. You had a very late meal, or your meal was too high in carbohydrates.
  2. Your body is experiencing stress (or higher than normal allostatic load), the rise in cortisol (stress hormone) could potentially raise your blood sugar level. Whether you’re running away from physical danger, or been working 24/7 to meet a dateline; our body cope with similar mechanisms. It reacts with “fight, flight, flee/freeze”. This could cause an increase in blood sugar level, which in turn could be ultilised as energy to defend for our lives.

You may want to test at the same time each day, as over a period of time you may be able to see a response pattern. Other times to test could be around meal times.

Urine, breath or blood test strips?

Every way of measuring ketones or anything for that matter, has its pros and cons. The method of choice should be based on what you are trying to optimise.

Blood ketone strips are shown to be as accurate as conventional lab tests. The strip measures beta-hydroxybutyrate (BHB) which is the primary ketone. Reading above 0.5mmol/L seems to supposedly shift the fuel usage from glucose to ketones. All the machines listed Abbott Optium, LifeSmart (Aus) or KetoMojo (US) also measure blood glucose. However, you will need to purchase the blood glucose strips for glucose testing. This could be useful if you’re tracking the Glucose Ketone Index (ratio of glucose to ketones) for specific health conditions. Cons: Can be expensive with multiple testings and painful as you have to prick your finger each time (ouch!).

Urine test strips measures acetoacetate, which is another ketone. The test produces a relative colour change depending on how much acetoacetate is detected in the urine. This method is easy and inexpensive. Cons: The results may be affected by medications and health conditions, hence giving you a false negative or positive. And after several weeks of ketosis, the kidney adapts to the level of ketones. This could result in a mismatch between the sample and the circulating ketone level.

Breath test measures acetone, which is also a ketone. Some research shows a correlation between acetone and blood ketone, beta-hydroxybutyrate. This method is portable and easy to use. Cons: Results could be affected by large consumptions of certain foods, such as coffee, tea or garlic. Test could also give a false positive result if you have Small Intestinal Bowel Overgrowth (SIBO). SIBO is a huge topic, many patients I see have SIBO. For reliable information, visit: Dr Alison Siebecker has very generously shared a lot of free resources on this topic.