I’d like to keep things short and simple. I’ve seen a lot of folks discussing over the Internet and advising each other to use blood ketone monitoring systems as the urine ketone strips are useless and how they give a lot of false positives.
I believe that if you know how to use them and when to use them, they can be more than efficient.
I do not advise folks who just start on very-low-carb-high-fat nutrition to buy expensive ketone meters because they may not stick to the diet for the long-term and the ketone meter will just add to the list of unused objects that fill-up the closet.
I think that one doesn’t need to know that his ketone levels measure 2.83297 mmol/L (that you would get using a blood ketone meter). I find it sufficient to know that your ketones measure between 1-3 mmol/L (a type of measure that you can get using urine ketone strips) and that you are in ketosis.
You can find the science between ketones, ketone levels, and ketone measurement systems in my recent Ketone Power.
Avoiding bad measurements
Most of us have higher cortisol (for ~first 30 minutes of the day) and blood glucose levels upon waking. This would negatively impact ketone production and the urine strips would show lower ketone traces.
I’d also say that the measures are affected if used post-prandial (after eating) because of the insulin response to the meal (even under low-carb nutrition – though I have to do more research on this).
Glucose levels are higher during and immediately after exercising even when following ketogenic nutrition plans. Peter Attia’s metabolic chamber experiment shows this clearly. However, a keto-adapted individual would start increasing ketone production and enhance the fat oxidation process several minutes after exercising.
Lastly, water intake may “dilute” the ketones, thus affecting urine ketone measures.
So, when should I measure?
Based on my personal experience, I’d recommend using them 1-2 hours upon waking or 1-2 hours after breakfast (in case you have breakfast). Also, make sure you haven’t consumed a lot of water 1-2 hours before measuring. I’d also recommend measuring ketone levels through ketone strips 1-2 hours post exercise.
I wrote more about my experience with these strips in Ketone Power.
If you know something useful and interesting about the urine strips, please share it with me in either of the comment sections below. If you’re unclear about something, I’m here to help.