How Long Does It Take to Get Into Ketosis? You cannot simply jump into ketosis in a 24-hour timespan. Your body has been burning sugar for fuel your entire life. It will need time to adapt to burning ketones for fuel, this transition could take anywhere from 48 hours to one week. The length in time will vary depending upon your activity level, lifestyle, body type and carbohydrate intake; using the ketone meter to track your ketone content, and you just need to breathe with it Ketone breath meter with 4 LCD Display colors for indications: 0 reading with WHITE background, 0.1-2.9 readings with GREEN background, 3.0-4.9 readings with YELLOW background and over 5.0 readings with RED background; powered by 2*AAA batteries (not included but commonly available) In order to get accurate ketone readings, please exhaust the residuals completely with the ketone meter before your first use by running the keto breath tester 3 times without blowing, because each ketone breath analyzer was tested during the production before shipping to warehouse, there maybe residuals; if you want to test another person consequently after your testing, please also kindly exhaust your previous residuals