Record your weight at the same time each day. First thing in the morning is best (this is normally your lowest weight of the day).

Note: day to day weight variations of 2-3 lbs (1-1.5 kg) are common. These can occur for a variety of reasons, including retained water, bowel movements, menstrual periods, etc. Don't be overly alarmed if your weight goes up 2 lbs in one day (and, conversely, don't be too thrilled if your weight goes down this much in one day).