Weight Loss Injections: What They Are and How to Track Your Journey

The most widely recognised weight loss injections currently prescribed worldwide belong to a class of medicines called GLP-1 receptor agonists. Wegovy contains semaglutide; Mounjaro contains tirzepatide, which acts on both GLP-1 and GIP receptors — making it a dual agonist. Both are administered as once-weekly subcutaneous injections using a pre-filled pen device.

How they act on the body

These medicines mimic hormones involved in appetite regulation. Many people experience a reduced sense of hunger, increased fullness after smaller amounts of food, and a quietening of persistent thoughts about eating (sometimes called "food noise"). They also slow gastric emptying, which contributes to the feeling of fullness — though this effect commonly eases over time.

Because these are prescription-only medicines, suitability and dosing are always decided by your prescriber or doctor based on your individual health history. GLP Trackr is not a prescriber or medical service and does not supply or source any medication. If you are looking for information on how to obtain a prescription, your own healthcare professional or a registered pharmacy in your country is the right starting point.

Common injection sites and rotation

Weight loss injections are typically administered into the fatty tissue of the abdomen, upper thigh, or upper arm. Rotating between sites with each injection helps reduce the chance of irritation or tissue changes at any single spot — something your prescriber or the patient information leaflet with your pen will cover. Our guide to weight loss injection basics explains what people on these treatments commonly experience, and you can read more on comparing weight loss injection options for a factual overview of the main medicines available.

What about other injection names you may have heard?

You may have come across the names Ozempic (also semaglutide, primarily prescribed for type 2 diabetes) or liraglutide (an older GLP-1 medicine). For a closer look at how Mounjaro fits into this picture, see our page on Mounjaro and its use in diabetes management. The broader weight loss injections hub covers the full landscape of currently prescribed options.

Keeping track of injection sites is one of the most practically useful things you can do once you are established on a weekly injection — and it is exactly what GLP Trackr is built for.

The app's injection-site tracking and rotation feature lets you log each injection: which site you used (abdomen, thigh, or arm), the date, and the dose strength. GLP Trackr then tracks your rotation history and suggests your next site automatically, so you never have to try to remember where you injected three weeks ago. Paired with dose reminders, the app means a weekly shot is far less likely to slip your mind during a busy week.

If you experience side effects — nausea, fatigue, injection-site reactions, or anything else — the side-effect log lets you record how you feel over time. Spotting patterns in your own data is far easier when it is all in one place, and it gives you something concrete to bring to your next prescriber appointment rather than trying to recall details from memory. You can explore how other aspects of the journey fit together on our page about what to expect on a weight loss injection, or see how making the most of your Mounjaro prescription relates to staying consistent.

If you have any concerns about symptoms — particularly anything severe, persistent, or unusual — contact your healthcare professional promptly. GLP Trackr helps you record what is happening so you can discuss it clearly with your prescriber; it is not a substitute for their guidance.

Ready to take the guesswork out of injection-site rotation? GLP Trackr is available free on the App Store and Google Play — log your first shot today and start a 7-day free trial.