The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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Mounjaro Not Suppressing Appetite — What You Need to Know
If you're taking Mounjaro (tirzepatide) and not noticing appetite suppression, you're not alone — this is a common experience, especially in the early weeks. Appetite reduction typically develops gradually as your dose increases, and several factors can affect how much appetite suppression you experience. This guide explains what's normal, when to expect changes, and when to contact your prescriber about your experience with the medication.
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What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
How Mounjaro Works and When Appetite Suppression Starts
Mounjaro is a dual GIP and GLP-1 receptor agonist — it works by activating two natural hormone pathways that help regulate appetite and blood sugar control. Unlike some other weight loss medications, Mounjaro's appetite-suppressing effects typically develop over several weeks as your dose increases, not immediately.
Most people notice appetite changes starting around week 2 to 4, but significant appetite suppression often doesn't occur until you reach a higher maintenance dose — typically 7.5 mg or above. The dose titration schedule is gradual: you start at 2.5 mg, then increase by 2.5 mg increments every 4 weeks, reaching a maximum of 15 mg. This slow escalation allows your body to adjust and your prescriber to find the dose that works best for you.
- Weeks 1–4: 2.5 mg starting dose — minimal appetite changes expected
- Weeks 5–8: 5 mg — mild appetite reduction may begin
- Weeks 9–12: 7.5 mg — more noticeable appetite suppression for many people
- Weeks 13+: 10 mg and above — stronger appetite effects typical
If you're on a lower maintenance dose or still in the early titration phase, lack of appetite suppression is very normal and does not mean the medication isn't working.
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If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
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Why Mounjaro May Not Be Suppressing Your Appetite
Several factors can explain why appetite suppression hasn't developed yet or isn't as strong as you expected:
- Still on a low dose: Appetite suppression is dose-dependent. If you're still on 2.5 mg or 5 mg, you may not experience significant appetite changes yet.
- Early in treatment: It can take 4–8 weeks of consistent use at a therapeutic dose before appetite reduction becomes pronounced.
- Individual variation: Not everyone experiences appetite suppression equally. Some people notice it quickly; others develop it more gradually.
- Stomach adaptation: If you've been taking Mounjaro for several weeks, your stomach may have adapted, and initial nausea that naturally reduces appetite may have worn off.
- Medication interactions: Certain medications or supplements can affect how Mounjaro works. Oral contraceptives, for example, may have reduced absorption when taking Mounjaro.
- Lifestyle factors: High stress, poor sleep, or inconsistent meal timing can mask appetite suppression effects.
Use our GLP-1 weight loss calculator to set realistic expectations for your dose and timeline.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
How long does it take for Mounjaro to start suppressing appetite?
Most people notice mild appetite changes within 2–4 weeks, but significant appetite suppression typically develops around weeks 8–12 as your dose increases. The full appetite-suppressing effect often isn't noticeable until you reach a maintenance dose of 7.5 mg or higher. Individual timelines vary considerably.
Is it normal to feel hungry on Mounjaro?
Yes, especially if you're on a lower dose or early in treatment. Hunger on Mounjaro doesn't mean the medication isn't working — appetite suppression is dose-dependent and develops gradually. If you reach 10–15 mg and still feel constantly hungry, discuss this with your prescriber.
What should I do if Mounjaro isn't suppressing my appetite?
First, confirm you're at an adequate dose (ideally 7.5 mg or higher) and have been on it for at least 6–8 weeks. Review your injection technique and storage. Contact your prescriber if appetite remains unchanged — they may adjust your dose, assess for medication interactions, or explore whether Mounjaro is the right choice for you.
Is Mounjaro different from Wegovy for appetite suppression?
Yes. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials suggest Mounjaro may produce slightly stronger appetite suppression on average, but individual responses vary. Some people respond better to one than the other.
Can I combine Mounjaro with other appetite suppressants?
Never combine Mounjaro with other weight loss medications without explicit prescriber approval. Combining medications can increase side effect risks. Your prescriber will assess whether additional treatment is needed or if adjusting your Mounjaro dose is more appropriate.
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