GLP-1 Tracker: What to Log and Which to Use (October 2026)

01 · The core answer

Do you actually need a GLP-1 tracker?

Yes, in practice most people benefit from one, because a once-weekly injection is easy to lose track of. Mounjaro is a once-weekly pen, and the dose steps up over time, so knowing which strength you used and when matters.¹ A simple log answers the questions you will be asked at every review: which dose, how have you felt, and what has your weight done?

You do not need anything sophisticated. A tracker has three jobs: remember your injection day, show your trend, and record what changed after each dose step. Anything that does those three things is enough.

02 · What to record

What to log each week

Log the same few things every week so the data is comparable.

If you are on Mounjaro, the Mounjaro pen and its consultation page explains the six strengths and how ordering works. Each order includes needles, a sharps bin and injection guidance.

03 · What to do next

Choosing your tracking method

Pick the method you will still use in several weeks. Dedicated apps suit people who like reminders. A spreadsheet suits people who want control. A paper chart suits people who prefer to tick a box on the fridge door. Our printable weight loss tracker is a simple option, and the free tracker guide compares no-cost approaches. If you want to start treatment, our weight loss clinic explains the pathway.

04 · Apps compared

GLP-1 tracking apps and online tools

Several kinds of tool exist, and they differ mainly in how much they log. Some focus on dose reminders and injection-site rotation. Some add food diaries. Some are web calculators that draw an estimated medicine-level curve from your dosing schedule.

Our own GLPTrackr is a free companion app for tracking a GLP-1 journey on iOS and Android. For a wider comparison, see our guides to the best tracker apps and a GLP-1 app tracker, which look at what each type does well.

Whatever you choose, look for these basics: weekly reminders, a dose history, site rotation, a weight chart and the ability to export or show your log at a review. Be cautious about any app that tells you to change your dose on its own. Dose decisions belong to your prescriber.

05 · Reading your results

How to read your weight trend

Judge progress by the trend over several weeks rather than one weigh-in. Weight moves up and down with fluids, meals and routine, so a single reading says little.

Published trial figures give useful context, but they are averages. In the SURMOUNT-1 trial of 2,539 adults, people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.² These are trial averages — individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.²

So a slower week or a plateau does not mean treatment has failed. Note it in your log, keep the other habits steady, and raise it at your next review. Our Mounjaro weight loss tracker page goes into the detail, and the GLP-1 statistics guide puts averages in context.

06 · Side effects and reviews

Using your log for side effects and reviews

A dated side-effect log makes your prescriber's job easier and your own concerns clearer. Record what you felt, roughly when it began relative to your injection, and how long it lasted. This is especially useful in the weeks after a dose step.

If you notice a new or lasting symptom, tell your prescriber rather than waiting. You can also report suspected side effects through the MHRA Yellow Card scheme.¹⁹ Mounjaro slows stomach emptying, which can reduce how well oral contraceptive pills are absorbed.⁷ The SmPC advises switching to a non-oral method, or adding a barrier method (such as condoms), for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.¹

Our service includes ongoing monthly reviews, dose titration and follow-up assessments by the prescribing team, and repeat orders re-check suitability. Bringing a clean log to those reviews means decisions rest on what actually happened.

07 · Medicine levels

Estimated medicine-level graphs: useful, but limited

Some trackers draw a curve of estimated medicine in your body. Tirzepatide has a half-life of about five days, so after a final dose it takes roughly four to five weeks to clear the system. There is no way to speed this up, and nothing needs doing while it clears.¹

Treat such graphs as an illustration, not a clinical tool. They estimate rather than measure, and they cannot tell you whether to take, delay or change a dose. If you miss a dose, take it as soon as you can within 4 days (96 hours) of the scheduled time; if more than 4 days have passed, skip the missed dose and take the next one on your normal day — never take two doses within 3 days of each other.¹³

Also keep storage in your log if it helps: keep pens in a fridge at 2–8°C and never freeze them; once in use, a KwikPen can be kept out of the fridge at a temperature not above 30°C for up to 30 days after first use, and must then be thrown away.¹³

08 · Food and activity logs

Food and activity: do you need to log them?

You do not have to log every meal, but a rough record helps. Mounjaro is used alongside a reduced-calorie diet and increased physical activity, so it is worth noting how you are eating and moving.

General food diary apps such as MyFitnessPal are not GLP-1 specific, but they can record meals, and many people pair one with a dose tracker. Pick whatever you will actually keep up. How much you should eat on treatment is a question for your prescriber or a dietitian, as it depends on your size, activity and health.

Many people find protein, hydration and smaller meals useful topics to raise at reviews, and a simple note of how full you felt after meals gives your prescriber real information to work with.

09 · Serious side effects

Serious side effects: when to get help straight away

Serious side effects are uncommon but need urgent attention. Seek immediate medical help for: severe, persistent stomach pain that may spread to your back, with or without vomiting (possible pancreatitis); pain in the upper right abdomen, fever or yellowing of skin/eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing. If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion) — your prescriber may need to adjust those medicines.¹

10 · Tracking supply

Tracking your pens and reorders

Log when each pen starts and finishes, so you reorder in good time. Repeat orders re-check suitability and there is no auto-shipping, so planning ahead avoids a gap in your weekly schedule. Our guide to a supply tracker explains how to keep an eye on pens and availability. All six doses are in stock, and delivery is free next-day tracked, with same-day dispatch when ordered by 3pm.

For a visual summary of how these medicines work, our GLP-1 infographic is a handy reference.