Don’t. I got a cheap one, which sometimes gave me a modest reading, but other times a zero when I couldn’t understand why that would be. I didn’t really trust it.
Then I asked for a Ketonix for Xmas since at least it would head off my wife from getting me a present I wanted even less. I get REALLY high readings most of the time. Either I’m a keto champ or I’m eating too many carbs. “Wait, what?” you say? How can a high reading mean both of those things? Well, my daughter, who lives only on carbs, blows high numbers. They even have a FAQ answer to the question “Why is my daughter/husband/neighbor blowing red?”
And it says:
"They eat pizza, fries and drink beer, is the simple answer!! When you received your KETONIX, you are likely to test it all the time. When doing so, a normal reaction from others is to see if they are are burning a lot of fat (even if they don’t follow a low carbohydrate, high fat diet).
Eating carbohydrate rich food and looking for ketones does not make sense. The body does not produce that much ketones while there is available circulation carbohydrates, unless you have diabetes type 1 and have very high blood sugar values.
However, the KETONIX reading may be high on high carbohydrate diets, but that is not from ketones metabolism. It will be from the process of breaking down those carbohydrates. This process is done via bacteria, called probiotics in your gut. If too much of this bacteria could cause a slowdown of your metabolism. There are studies that connects the probiotics to obesity and other metabolic issues relating to brain chemistry.
So, use our KETONIX for the intended use. For example: If you eat pizza and drink a beer then look for ketones … you are not using it as intended."
So, the Ketonix is a terrible false-positive generator! If you get a high reading, EITHER you are in heavy ketosis, OR you are eating too many carbs. So, if it shows a zero reading, you have zero ketones (and you can trust that interpretation), but if you have a high reading, either you have high ketones OR zero ketones. You don’t know which. Real helpful, right?
The cheap ones at least have the virtue of being cheap.