Many people try to buy ketogenic meals online or make their own ketogenic meals at home, but it is difficult to tell whether they are in ketogenic status. For this reason, we developed CKM, a sensor that can monitor blood ketone data in real time, so that users can see whether they are in a ketogenic state, and can compare the ketogenic effect of different meals at different times, so that they can better adjust their diet and improve the effect of ketogenic fat loss.