Mounjaro is tirzepatide, taken as a weekly injection. It is licensed for type 2 diabetes, and in some markets for weight management under specific criteria, which is why NICE guidance on tirzepatide for overweight and obesity sets out particular clinical circumstances rather than a blanket use. Whatever the reason you are using it, tracking weight in a way that is genuinely useful means comparing your own numbers against your own starting point, not against a figure you saw quoted somewhere else.

Weight is not a single, stable number

Cleveland Clinic explains that body weight naturally fluctuates from day to day because of factors like hydration, recent food intake, sodium, hormonal changes, and even the time of day you weigh yourself. A reading that is a little higher or lower than the day before is not automatically meaningful on its own. Treating any single weigh-in as a verdict on how things are going tends to create more anxiety than information.

Setting a baseline and a check-in rhythm

Before anything else, record your starting weight clearly, along with the date. From there, a weekly or fortnightly check-in, done under roughly the same conditions each time, gives you a trend line rather than a series of disconnected numbers. Consistency in conditions matters more than frequency:

  • Weigh at a similar time of day, ideally before eating or drinking.
  • Use the same scale if possible, on a hard, flat surface.
  • Wear similar clothing, or note when you didn't.
  • Record the number alongside the date rather than relying on memory.
  • Note anything unusual that day, such as illness, travel, or a change in routine.

Working out your own percentage change

CDC guidance on losing weight highlights the value of keeping records as part of monitoring your own progress. A simple way to see change over time, without needing anyone else's numbers for comparison, is to work out the percentage difference between your current weight and your baseline weight. Because this is your percentage against your own starting figure, it stays meaningful regardless of your height, starting weight, or how quickly or slowly things change for you personally.

A few extra measures worth considering

Weight is not the only number that can be worth logging alongside your baseline. Some people find it useful to also note waist measurement, how a particular pair of trousers or a belt fits, or general energy levels, since these can sometimes tell a fuller story than the scale alone, especially during weeks where weight itself barely moves. None of these additional measures need to be extensive; a single consistent number, tracked the same way each time, is more useful than several inconsistent ones.

Reading a trend line instead of a single number

Once you have several weeks of entries, plot or simply skim them in order rather than jumping straight to the most recent figure. A trend line smooths out the day-to-day noise that Cleveland Clinic describes and shows the general direction more honestly than any single weigh-in can. It is normal for a trend line to include weeks that are flat, or that move in the opposite direction to the overall pattern; that is exactly why looking at the shape of the line over a month or more is more informative than reacting to any individual data point.

It can also help to record how you felt about your weight that week alongside the number itself, separate from the figure. Weight tracking can become stressful if every entry feels like a test, and separating the factual number from your emotional reaction to it, even just in a short note, can make the habit easier to sustain over the months a course of treatment might last.

What this record is not for

This kind of tracking is for your own reference and for conversations with your prescriber; it is not a way to judge whether Mounjaro is working the way it is supposed to, and it is not a basis for changing your injections, dose, or diet on your own. There is no typical or expected pace that applies to everyone, and comparing your trend to another person's, or to another medicine's published results, will not tell you anything reliable about your own situation. If your weight trend concerns you, or you notice rapid, unexplained change in either direction, that is a conversation for your prescriber, not a pattern to interpret alone.