The human body produces ketone body as a by-product when body fat burning starts, and such state is called ketosis.
As body fat burning progresses faster, ketone body amount increases. So you can find out how fast body fat burning occurs by measuring ketone body
amount inside your body.

What is ketone?
How to measure ketone?
Ketone body is composed of 3 substances: acetone, BOHB (β-hydroxybutyrate), and ACAC (acetoacetate).ACAC is measured by the urine, and BOHB is measured by the extracted blood. Acetone has intense volatility and emitted as respiration gas, so it can be measured by an exhaled breath and it is the method of measuring ketone state of KETOSCAN.
What are the advantages and disadvantages of 3 ketone measurements?
ACAC measurement using urine strip is the low-cost measurement, but the result can be found only with keto stick color changes, and it is variable
according to the amount of urine, so it is difficult to measure the quantitative ketone state. Until now, blood measurement using BOHB is most generalized and known to be the most direct way to find out ketone states, but ketone strips are expensive, and most of all, the most significant disadvantage is that you have to get blood for every examination.
Acetone measurement has the advantage of straightforward analysis like blowing into a breathalyzer, but it needs to detect very low concentration
acetone (1/1,000,000 ppm), so it requires high-level sensor technology, and it is the biggest reason for none-commercialization so far.
What does acetone reading mean?
The starting point of ketosis that human body starts to use body fat as primary energy is from 2 ppm of acetone, and at this time, body fat is known to be decomposed by about 1g per hour. As acetone concentration is higher, body fat burning faster, but the high level is not always good, and the most optimal section for diet is 10~40 ppm. If it is higher than that, an unnecessary ketone is excessively accumulated in the body, which is not beneficial for the human body, and in a very high concentration of 60ppm or higher, if it is along with high glucose, there is also a danger of ketoacidosis, so the level has to be adjusted.