When to Use Ketostix: Do They Work?

Are Ketostix useful - Should you use Ketostix to Measure Ketosis. Are they telling you what you want to know or just half the story?

Seeing purple on the Ketostix doesn't also mean what you think it means. They measure excess ketones and only measure one of two major ketones and thus are unreliable for measuring whether you are in ketosis or not. You cannot use them to titrate your carbs.

Factors affecting color/readings on the Ketostix:

Dilution - drink more water, the Ketostix level changes and if you drink enough it will read negative...false negative result Excess ketones - only measure excess, if you're using them all you won't have any excess excreted.

When you first start keto, your body overproduces ketones but with time and adaptation you produce just enough for your brain and thus no longer spill them into the urine, Ketostix will be negative...false negative result;

Eat a bunch of carbs, immediately inhibits ketosis and you return to glucose-based metabolism and thus your body has no use for ketones in circulation and you excrete them, many then check Ketostix and get a false security that they are in ketosis because they get a false positive result

Ketostix only measure acetoacetate - there are two major ketone bodies acetoacetate and beta hydroxybutyrate, Ketostix only measure the former; the longer you're in ketosis the more of the latter you have in circulation so if you are spilling excess Ketostix can't detect it and you get a false negative

Consume exogenous Ketones = purple shows up on the sticks...of course they do you just drank Ketones; another false positive and you are not in nutritional ketosis.

They are intended for diabetic ketoacidosis, not nutritional ketosis and often seem to cause confusion, frustration and false security because many people don't know how they work and yet continue to use them in a way that they hope they work.

Amy Berger, a Certified Nutrition Specialist (CNS) and certified Nutritional Therapy Practitioner, explains it nicely here:

I’m not saying ketostix are useless for providing any other information besides whether or not there is acetoacetate in your urine. We can certainly use ketostix to speculate about issues other than the presence of acetoacetate, but that’s all it is—speculation, based on your diet, activity levels, stress levels, and more. They provide information, but they do not always provide answers. Are you showing deep purple on your urine test strips but not losing body fat? All that tells you is that being in ketosis doesn’t guarantee fat loss. (Which you already knew, right? Right?!) It doesn’t tell you why you’re not losing fat.