The best time to check your blood ketone levels to verify you are in optimal ketosis is first thing in the AM prior to eating. Although you haven’t been actively fasting, being asleep keeps you from eating, so in essence, you are checking a fasting blood level.
This assumes you are using a ketone testing meter. If you are checking urine ketones using test strips, you should urinate as soon as you get up and then test the next time you urinate. Preferably, this would be before eating, as eating will change your ketone level.
Urine test strips have a little lag time since your body has to digest food, make ketones and circulate through the system before being removed by the kidneys and excreted.
So, even if you test your urine right after you eat, it should be OK. Testing >30 minutes after eating may not give you accurate results.
Blood ketone test strips can be expensive, so many people that use them, use them sparingly. Once you are in optimal ketosis, you can start testing less often. One day a week, first thing in the morning should be adequate for ongoing monitoring as long as your eating habits are stable.
If you change your diet, aren’t very good at monitoring carbs, or have a cheat day, you might want to check more often. In fact, we recommend that you test daily after a cheat day until you have two mornings in a row with blood levels above 1.3 mmol/L.
Optimal starts at around 1.5 mmol/L, but once you have two days in a row above 1.3 mmol/L, it should be safe to stop checking daily. Until the next time something changes, that is.
These numbers are for blood ketone testing. Urine ketone testing results are usually listed as milligrams per deciliter. To convert, just move the decimal place to the right. 0.5 mmol/L for blood results would equal roughly 5 mg/dL on urine test strips.
If you are the type of person that wants to constantly know your ketosis status, you can use urine test strips regularly, and then cross-check questionable results with a ketone testing meter.
There are three things to remember though. First, you must verify that the test strips have not expired. They can become worthless once they expire and you can make decisions based on faulty data.
Secondly, urine test strips are not very accurate and can fluctuate dramatically based on your fluid intake. The final thing to keep in mind is that urine test strips have an unusual scale.
The only results you get are either “negative” or at ~5 mg/dL, 15 mg/dL, 40 mg/dL, 80 mg/dL, and >160 mg/dL. The actual numbers may vary by test strip manufacturers, but they are all around similar levels.
Your results with urine test strips can only be accurately stated as “not in ketosis” (negative result), “barely in ketosis” (5 color or darker, but not as dark as 15), “optimal ketosis” (15 color or darker, but not as dark as 40), “higher than optimal” (40 color or darker, but not as dark as 80), which is not necessarily a bad thing, but you may be able to add more carbs without impacting your ketosis, “too high” at 80 mg/dL, and “dangerously high” at 160 mg/dL.
If your urine ketones are 160 or greater, you may be experiencing an issue with your diet and should seek medical attention. Your blood may be too acidotic, called ketoacidosis, which can be very dangerous.
This is specifically a problem if you have ever been diagnosed as diabetic, either Type I or Type II or you are being monitored as “borderline”. Short of having diabetes or a few other rare conditions, no one in dietary ketosis should ever get that high of a ketone reading.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.