The easiest and cheapest way to measure ketones is by using urine keto strips. These will tell you if you are in ketosis, but they are not always accurate when it comes to your exact ketone levels. Hydration and electrolyte levels can impact the results . Normally, a pink or purple color on the keto strip means ketones are being produced in your body. If the color is darker, it could simply mean ketone levels are more concentrated in your urine.
On the other hand, a more accurate way to measure ketones is by using a blood meter . This is done in the same way you would check your blood for glucose — by pricking your finger and squeezing a drop of blood out onto a stick and placing it inside the device. This way of measuring ketones is expensive also because a new strip is needed each time. Knowing your blood ketone levels is very useful information, though, especially if you are on a Restricted Ketogenic Diet and numbers are important to you. Measurements are shown in mmol/L (millimoles per Litre).
You can also use a ketone breath meter too which tests for acetone. Even though acetone is an indirect measure, it is correlated to ketones in the blood . This device has the advantage of being a one-time purchase (no strips needed).
You can also look for symptoms that indicate you are in ketosis: a clearer mental state, less hunger, sustained energy, increased thirst, and better skin . You can also experience uncomfortable symptoms like headaches due to dehydration as you start to enter ketosis.
A smell of acetone on your breath can also mean you're in ketosis . Acetone has a fruity smell and some describe it as smelling like nail polish remover. However, you can’t rely on the smell of your breath to gauge if you’re in ketosis as it could also indicate a potentially dangerous state. Having the taste or scent of “fruity breath” in your mouth can also be due to ketoacidosis, which is a rare and dangerous condition that you're most likely to have if you suffer from type I diabetes .