What Are Peptide Injections for Weight Loss?
The term peptide injections for weight loss most commonly refers to GLP-1 receptor agonists — and, in the case of tirzepatide, dual GIP and GLP-1 receptor agonists. These are synthetic peptides that mimic naturally occurring gut hormones involved in appetite regulation and feelings of fullness.
How they are taken
Both Mounjaro and Wegovy are administered as a subcutaneous injection — meaning just under the skin — once a week. They come as pre-filled pens designed to make the process as straightforward as possible. The three most commonly used injection sites are the abdomen, the front of the thigh, and the upper arm. Rotating between these sites each week is generally recommended to allow the skin and tissue time to recover between doses.
What people commonly report
Experiences on weight-loss peptide injections vary considerably from person to person. Many people report a noticeable reduction in appetite and food cravings — sometimes described as quieter "food noise". Gastrointestinal effects such as nausea, constipation, or loose stools are among the most commonly reported side effects, particularly in the earlier weeks or after a dose is adjusted by a prescriber. Injection-site reactions (mild redness or tenderness at the site) are also frequently mentioned. These are general patterns drawn from widely reported experiences; your own response will depend on your individual health, history, and how your prescriber has structured your treatment.
For a broader overview of these medicines and how they are used, see our guide to weight-loss injections. You may also find it useful to read about what injections for weight loss involve and common questions about weight-loss injections.
average weekly weight change in the first 16 weeks of Mounjaro & Wegovy use*
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Tracking Your Peptide Injection Journey with GLP Trackr
One of the most practical things you can do when taking a weekly injection is keep a clear record of where you last injected — and GLP Trackr's injection-site tracking and rotation feature is built exactly for this. Each time you inject, you log the site (abdomen, thigh, or arm), and the app tracks your rotation history so it can suggest your next site automatically. It takes seconds, and it removes any guesswork about whether you are varying your sites correctly.
Beyond site rotation, the app also lets you log the date, time, and dose strength of each injection, so you always have an accurate record to refer back to or share with your prescriber at appointments. If you notice patterns in how you feel after each shot — energy levels, nausea, mood — the side-effect and daily check-in tracking lets you capture those observations over time, making it much easier to have an informed conversation with your healthcare professional.
You can also explore how injection-based weight-loss treatments are generally used for more background context.
Safety note: GLP Trackr helps you record your journey and spot your own patterns — it is not a substitute for guidance from your prescriber or doctor. If you experience side effects that feel severe, persistent, or concerning, contact your healthcare professional promptly. Any questions about your dose, injection technique, or whether this medicine is right for you should always go to the clinician who prescribed it. If you believe you need to report a side effect formally, your prescriber can advise you on your national reporting scheme (such as the UK's Yellow Card scheme).
Ready to take the guesswork out of injection-site rotation? 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.
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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.
Peptide injections for weight loss refer to prescription medicines such as Mounjaro (tirzepatide) and Wegovy (semaglutide). They are once-weekly subcutaneous injections that act on appetite-regulating hormone pathways. They are prescription-only and must be obtained through a prescriber.
Commonly reported side effects include nausea, constipation, diarrhoea, and mild injection-site reactions such as redness or tenderness. These are most frequently noted in early weeks or after dose adjustments. Experiences vary; always discuss side effects with your prescriber or doctor.
Rotating injection sites — between the abdomen, thigh, and upper arm — is generally recommended so that skin and tissue can recover between doses. Your prescriber or the patient information leaflet that came with your pen will give guidance specific to your medicine.
GLP Trackr lets you log each injection's date, time, dose, and site, tracks your rotation history, and suggests your next site automatically. It also lets you record side effects and daily wellbeing so you can spot patterns and discuss them with your prescriber.
Real-world experiences vary widely. GLP Trackr's community feature connects you with others on Mounjaro and Wegovy who share their journeys. For clinical information about these medicines, the electronic Medicines Compendium (medicines.org.uk) holds the official product information.