After you eat your last meal it then takes your body from 8 to 12 hours to be in the full fasting state.
After 12 hours since your last meal your body should be in the full fasting state and can then burn off the fat and glycogen in your body.
Your body will then peak at it's fat burning process after 14 hours of being in the fasting state and you should start to lose weight even if it's not noticeable.