Keto stix can be helpful when you first start a ketogenic diet. They don't actually measure ketones, they measure excess ketones that are spilled into your urine. This happens when your body is not efficient at burning fat, and it can be an inexpensive way to know that you are in ketosis. Once your body becomes more efficient at burning fat, the number of excess ketones will drop, and you may not be able to detect ketosis using the keto stix anymore.
You can also check with a breath meter, but the accuracy from device to device or from a single device over time is questionable. What you eat or drink for 30 minutes to an hour before using them can throw off the readings and alcohol throws them off for up to 24 hours. They also can be sensitive to gases in the environment, including gases from cooking in a kitchen, or aerosols from things like hairspray or cooking spray.
The best way to detect you are in ketosis is when a blood ketone meter. It will actually check your blood for ketones, showing your current state of ketosis.
You can also check with a breath meter, but the accuracy from device to device or from a single device over time is questionable. What you eat or drink for 30 minutes to an hour before using them can throw off the readings and alcohol throws them off for up to 24 hours. They also can be sensitive to gases in the environment, including gases from cooking in a kitchen, or aerosols from things like hairspray or cooking spray.
The best way to detect you are in ketosis is when a blood ketone meter. It will actually check your blood for ketones, showing your current state of ketosis.