What Are the Slimming Injections and How Do They Work?
Mounjaro and Wegovy belong to a class of medicines that act on appetite-regulating pathways in the brain and digestive system. Here is a factual overview of each:
Mounjaro (tirzepatide)
Mounjaro's active substance is tirzepatide, a dual GIP and GLP-1 receptor agonist. It is given as a once-weekly injection using a pre-filled pen. Many people commonly report increased feelings of fullness and reduced appetite — sometimes described as a quietening of "food noise" — alongside slower stomach emptying, an effect that often becomes less noticeable over time. Mounjaro carries a Black Triangle (▼) designation in some countries, meaning it is subject to additional monitoring; any side effects should be reported to your healthcare professional and your national reporting scheme (such as the UK's Yellow Card scheme).
Wegovy (semaglutide)
Wegovy's active substance is semaglutide, a GLP-1 receptor agonist. Like Mounjaro, it is a once-weekly pre-filled injectable pen. Wegovy also acts on GLP-1 pathways to support feelings of fullness and appetite regulation. It similarly carries a Black Triangle (▼) designation in certain regions.
What they are not
Neither medicine is insulin, a cosmetic quick fix, or a substitute for clinical supervision, healthy eating, and physical activity. Suitability for either medicine is determined entirely by a prescriber — not by the medicine's informal name or reputation.
For a broader overview of how these medicines are used, see our guide to weight-loss injections. You may also find it helpful to read about whether the slimming injections are considered safe, and what the evidence currently suggests.
If you are researching access and availability, our page on slimming injections and how they are prescribed covers the general process in a worldwide-neutral way.
average weekly weight change in the first 16 weeks of Mounjaro & Wegovy use*
Tracking the right four numbers — weight, waist, protein and dose — turns a noisy chart into a clear story. That's the loop GLP-1 users keep coming back for.
AI Meal Tracking. Built for GLP 1 Appetites.
Point your camera at any meal and let our AI do the rest. Breakfast, doses, weight, mood all tracked in seconds.
Tracking Your Injection Journey with GLP Trackr
Once you are prescribed one of these medicines, staying on top of a weekly injection schedule — including which site you used last — is where many people find a dedicated companion app genuinely useful.
Injection-site tracking and rotation is the feature at the heart of GLP Trackr's injection support. Each time you inject, you log the site (abdomen, thigh, or upper arm) and the app keeps a rotation history, then suggests your next site automatically — so you are never trying to remember where you injected three weeks ago.
Alongside that, dose logging lets you record each injection with its date, time, and dose strength, giving you a clear, timestamped record that is easy to share with your prescriber at your next appointment. And if a weekly injection day is easy to lose track of, dose reminders can be set so a dose is never accidentally missed.
All of this lives inside one place — your personal GLP-1 journey log — rather than scattered across notes apps and memory.
You can explore what else the app tracks on our slimming injections overview page.
Any questions about your dose, injection technique, or whether a medicine is right for you should always go to your prescriber or doctor — GLP Trackr helps you record and organise your journey, but it is not a substitute for their clinical guidance.
Ready to keep your injection history in one place? GLP Trackr is free to try for 7 days — download it on the App Store or Google Play and start logging from your very first shot.
What does glptrackr include?
10+ powerful features. One app. Built specifically for Mounjaro and Wegovy users.
Everything your GLP-1 journey needs. Free to try for 7 days.
Morning Check-In
Start every day with a 60-second wellness check-in. Log how you're feeling, track nausea, appetite, energy, and mood — giving you and your care team a complete picture of how your medication is working.
Injection Tracking
Log every dose with a single tap. Track your dose history, phase in your cycle, estimated medication levels, and upcoming injection dates — with reminders so you never miss a scheduled shot.
Hydration Reminders
Staying hydrated is especially important on GLP-1 medications. Set daily water targets, log intake throughout the day, and receive smart nudges when you're falling behind your goal.
Smart Meal Planning
Personalized meal plans built around your current dose phase and side effects. Every meal is GLP-1 optimized — high in protein, gentle on the stomach, and scaled to your reduced appetite.
Recipe Library
Browse 50+ high-protein, GLP-1-friendly recipes filtered by meal type, prep time, and dietary needs. Every recipe includes full nutrition info, step-by-step instructions, and tips for eating with side effects.
Progress Analytics
Beautiful, easy-to-read charts show your weight loss trajectory, weekly nutrition trends, medication responses, and wellbeing scores over time — turning raw data into genuine insights.
AI Meal Scanning
Snap a photo of any meal and get a full nutrition breakdown in seconds — calories, protein, carbs, fat, and fibre. No searching. No manual logging. Just point, snap, and track.
Exercise & Steps
Log walks, workouts, and movement with activity targets that flex with your energy levels. On lower-energy dose days, gentler targets keep you moving without burning out.
Community Support
Connect with thousands of others navigating the same medication journey. Share milestones, ask questions, find accountability partners, and get support from people who truly understand.
Never Forget a Dose Again.
Log your Mounjaro or Wegovy injection in seconds. Track your pen, your dose level, and your injection site — so you always know exactly where you are in your treatment.
Watch Your Body Transform, Week by Week.
Log your weight, measurements, and how you're feeling after each dose. GLPTrackr turns your data into clear, motivating charts that show you how far you've really come.
You're Not on This Journey Alone.
Connect with thousands of real GLP-1 users sharing their wins, side effect tips, and meal ideas. Get the support of people who truly get it — because they're living it too.
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- Golden Dose Finder AI
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The Most Advanced GLP-1 Brain Ever Built.
The first AI built exclusively for GLP-1 weight loss. Every insight, every meal plan, every prediction trained on one thing only: helping you get the most out of your medication.
Knows Your Cycle
GLPIQ tracks where you are in your injection cycle and adjusts everything around it: lighter meals on nausea days, higher protein when appetite returns, and smarter targets as your medication level shifts.
Predicts Before You Feel It
GLPIQ learns your personal side effect patterns over time. After a few cycles, it starts warning you the morning before a rough day — and adjusts your meal plan automatically.
Finds Your Golden Dose
GLPIQ analyses every dose you've been on: weight loss rate, side effects, food noise, mood, protein adherence and tells you which dose gave you the best results. No other app does this.
Download glptrackr today.
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Frequently asked questions.
The two main prescription weight-loss injections are Mounjaro (tirzepatide) and Wegovy (semaglutide). Both are once-weekly injectable medicines prescribed by a healthcare professional — not available without a prescription.
Mounjaro contains tirzepatide, a dual GIP and GLP-1 receptor agonist. Wegovy contains semaglutide, a GLP-1 receptor agonist. Both are once-weekly injections. The right choice for any individual is a decision for their prescriber, not something to self-select.
Both medicines are prescription-only and approved by regulatory authorities in multiple countries, but suitability varies by individual. Always discuss safety, side effects, and any concerns with your prescriber or doctor, who knows your full medical history.
GLP Trackr lets you log each injection — including dose, date, and site — tracks your rotation history, and suggests your next injection site. It also sends dose reminders so a weekly injection is never accidentally forgotten.
Rotating injection sites is generally recommended to allow skin and tissue to recover. Common sites include the abdomen, thigh, and upper arm. For guidance specific to your medicine and circumstances, refer to your prescriber or the patient information leaflet supplied with your pen.