Percentage weight loss shows how much your weight has changed relative to where you started. It can be a clearer way to compare check-ins than pounds or kilograms alone, particularly if you are keeping notes for a GLP-1 review. It is still only one number. It cannot tell you whether a medicine is right for you or capture changes in appetite, symptoms, strength, or wellbeing.
Use this calculation: divide the amount of weight lost by your starting weight, then multiply by 100. In words, percentage weight loss equals weight lost divided by starting weight, multiplied by 100. Use the same unit for both weights. You can use kilograms or pounds, but do not mix them in the same calculation.
For example, someone who started at 100 kg and now weighs 95 kg has lost 5 kg. Divide 5 by 100 to get 0.05, then multiply by 100. The result is 5%. The same method works in pounds: a person who started at 220 lb and now weighs 209 lb has lost 11 lb; 11 divided by 220, multiplied by 100, is 5%.
Write down the date of your starting weight as well as the date of the current weight. Without dates, a percentage has little context. A change over two weeks means something different from the same change over several months, and neither figure explains the circumstances behind it.
For a steadier record, weigh in comparable conditions when possible: the same scale, similar time of day, and similar clothing. If you use daily readings, calculate from a weekly average or a regular weekly check-in rather than choosing the highest or lowest number. That helps keep normal day-to-day movement from distorting the result.
Use the percentage as a conversation aid, not a score. Alongside it, record how you have been managing meals, fluids, appetite, digestion, activity, and any side effects. Your prescriber can interpret those details in the context of your medical history and treatment plan. Do not change your dose, schedule, or medication because of a percentage calculation.