The Science Behind Each Injection: What Happens in Your Body
Both Mounjaro and Wegovy are once-weekly injectable medicines that mimic naturally occurring gut hormones involved in appetite regulation.
GLP-1 receptor agonism
Wegovy's active substance, semaglutide, is a GLP-1 receptor agonist. GLP-1 (glucagon-like peptide-1) is a hormone released after eating; it signals fullness to the brain, slows the rate at which the stomach empties, and reduces the drive to keep eating. By mimicking this hormone, semaglutide extends and amplifies those satiety signals — an effect many people describe as a quietening of constant food thoughts, sometimes called reduced "food noise".
Dual GIP and GLP-1 action (Mounjaro)
Mounjaro's active substance, tirzepatide, targets two receptors: GLP-1 and GIP (glucose-dependent insulinotropic polypeptide). GIP is another gut hormone involved in energy balance. Acting on both pathways simultaneously is what makes tirzepatide a dual agonist. The practical experience for many people — increased fullness and reduced appetite — is broadly similar to GLP-1 agonism alone, but the dual mechanism distinguishes it pharmacologically.
How the injection is given
Both medicines are supplied as pre-filled pens and are injected subcutaneously — into the fat layer just beneath the skin. Common sites are the abdomen, front of the thigh, and upper arm. The injection is given once a week, and rotating between sites is generally recommended to avoid tissue changes at any single spot. For detailed guidance on your specific pen and technique, always refer to the patient information leaflet supplied with your medicine or ask your prescriber or doctor.
For a deeper look at how the mechanism translates into real-world results, see our guide on how weight loss injections work in practice, or explore alternatives to weight loss injections if you are researching options to discuss with your prescriber.
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.
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Tracking Your Injections with GLP Trackr
Knowing how your injection works is only part of the picture — keeping a consistent, accurate log of every dose is what turns that knowledge into a clearer journey.
GLP Trackr's injection-site tracking and rotation feature is built specifically for this. Each time you inject, you log the site you used — abdomen, thigh, or upper arm — and the app records your rotation history, then suggests where to inject next. Over weeks and months, this makes site rotation automatic rather than something you have to remember manually.
Alongside site tracking, the app's dose logging captures the date, time, and dose strength of every injection, giving you a complete record to reference — useful if you ever need to recall your schedule or bring a summary to a prescriber appointment. Dose reminders help make sure a weekly injection is never accidentally missed.
You can also explore common questions about how weight loss injections work, or return to the full weight loss injections hub for a broader overview of managing your treatment.
Any questions about your injection technique, dose, or injection sites should be directed to your prescriber or doctor — they know your individual history and can give advice specific to you. GLP Trackr records your journey; it does not replace that clinical guidance.
Ready to take the guesswork out of injection-site rotation? Download GLP Trackr on the App Store or Google Play and start a free 7-day trial — your injection history, dose log, and next-site suggestion all in one place.
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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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.
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Frequently asked questions.
They mimic gut hormones — GLP-1 and, in Mounjaro's case, also GIP — that signal fullness to the brain and slow stomach emptying. This commonly reduces appetite and food noise. They are given as a once-weekly subcutaneous injection using a pre-filled pen.
Common injection sites are the abdomen, front of the thigh, and upper arm. Rotating between sites each week is generally recommended. Your prescriber or doctor and the patient information leaflet supplied with your pen are the best guides for your specific medicine and technique.
Repeatedly injecting in exactly the same spot can cause changes to the tissue beneath the skin over time. Rotating sites helps avoid this. Many people find tracking past sites helpful — GLP Trackr logs each site you use and suggests where to inject next.
This varies between individuals. Many people notice reduced appetite within the first few weeks, though the full effect often develops gradually over the course of treatment. Your prescriber or doctor is best placed to discuss what to expect based on your specific situation.
Yes. GLP Trackr lets you log each injection's date, time, dose strength, and site, tracks your rotation history, and can remind you when your next weekly dose is due — keeping your full injection record in one place.