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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How Long Does Mounjaro Take To Suppress Appetite?
Mounjaro (tirzepatide) typically begins to suppress appetite within the first few weeks of starting treatment, though the timeline varies between individuals. Many people report noticing reduced hunger and feeling fuller more quickly by weeks 2–4 of treatment. This appetite suppression effect builds as your dose increases during the titration phase. Our GLP-1 weight loss calculator can help you understand potential effects at different doses. The dual GIP and GLP-1 mechanism works differently from single GLP-1 medications like Wegovy, which may affect the onset and intensity of appetite suppression. Individual responses vary significantly, and your GP or prescriber can discuss what to expect based on your personal health profile.
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Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
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.
Mounjaro vs Wegovy: Appetite Suppression Timeline
Mounjaro (tirzepatide) activates two hormone pathways simultaneously — GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1). This dual mechanism may produce appetite suppression effects relatively quickly, with many users reporting noticeable reduced hunger by week 2–3 of the starting dose (2.5 mg). As your dose escalates weekly over the first 4–5 months toward the maximum 15 mg, appetite suppression typically intensifies.
Wegovy (semaglutide) is a single GLP-1 agonist. Clinical data from STEP trials shows appetite reduction onset is similarly within 1–2 weeks, though the mechanism is singular rather than dual. Wegovy reaches its maximum dose (2.4 mg) on a similar titration schedule.
Both medications slow gastric emptying (how quickly food leaves the stomach), which contributes to feelings of fullness. The dual mechanism of Mounjaro may theoretically produce a slightly different appetite profile, though head-to-head comparison data remains limited. Clinical trials (SURMOUNT for Mounjaro, STEP for Wegovy) both showed significant appetite reduction alongside weight loss.
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
What Affects Your Individual Appetite Response
Your personal experience of appetite suppression depends on several factors: starting dose and titration speed — faster escalation typically produces more noticeable appetite effects; individual metabolism and body chemistry — GLP-1 receptor sensitivity varies; existing diet and eating habits — appetite suppression is most noticeable when you're accustomed to larger meals; and presence of other health conditions — diabetes, gastroparesis, or digestive issues may affect response timing.
Both Mounjaro and Wegovy are prescription-only medications requiring clinical assessment. Your prescriber will personalise your dose escalation based on how well you tolerate each dose and your individual appetite response. Using our BMI calculator, you can track changes in your health metrics throughout treatment. Most people continue to see appetite suppression effects as long as they remain on the medication — if you stop, appetite typically returns to baseline within 1–2 weeks.
- 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 quickly does Mounjaro suppress appetite?
Most people notice reduced hunger within 1–2 weeks of starting the 2.5 mg dose, with effects becoming more pronounced as the dose increases during titration. Individual timelines vary — some experience appetite suppression very quickly, while others notice gradual change over 3–4 weeks. Your prescriber can discuss what to expect.
Is Mounjaro's appetite suppression faster than Wegovy's?
Both typically begin suppressing appetite within 1–2 weeks. Mounjaro's dual GIP and GLP-1 mechanism may produce a slightly different appetite profile compared to Wegovy's single GLP-1 mechanism, but clinical evidence shows comparable appetite reduction. Individual response varies more than medication type.
Does appetite suppression continue as Mounjaro dose increases?
Yes. As your dose escalates from 2.5 mg toward the maximum 15 mg, appetite suppression typically intensifies. Most people experience the strongest appetite suppression effects once they reach their target maintenance dose. Consistency in medication timing helps maintain these effects.
What happens to appetite if I stop taking Mounjaro?
Appetite typically returns to your pre-treatment baseline within 1–2 weeks of stopping Mounjaro. This is why the medication requires ongoing treatment — it doesn't produce permanent appetite changes. Discuss any planned changes with your GP or prescriber.
Can I get Mounjaro on the NHS in the UK?
NICE has approved tirzepatide (Mounjaro) for NHS specialist weight management services. Access varies significantly by region and availability through your local integrated care board. Your GP can refer you to tier 3 specialist services if eligible. Private access is also available through GPhC-registered online prescribers following clinical assessment.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.