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
Free tracker included with every download this week
Is Mounjaro Addictive? What the Evidence Shows
Mounjaro (tirzepatide) is not addictive in the traditional sense, but some people report difficulty stopping the medication. This is different from addiction. UK medical guidance clarifies that Mounjaro works on appetite and blood sugar regulation, not on reward pathways in the brain like addictive substances do. Understanding how Mounjaro works and what happens when you stop taking it can help you make informed decisions with your GP about whether this prescription medicine is right for you.
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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.
How Mounjaro Works and Dependency Concerns
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — it activates natural hormone pathways involved in appetite regulation and blood sugar control, not reward or pleasure pathways. This is a crucial distinction from addictive substances, which trigger dopamine release and create psychological dependence.
- Tolerance: Some users report that appetite-suppressing effects may reduce over time as the body adapts — this is tolerance, not addiction.
- Physical dependence: Stopping Mounjaro does not cause withdrawal symptoms like tremors, anxiety, or cravings typical of addictive drugs. However, appetite and hunger may return quickly.
- Psychological dependence: Some people find it emotionally difficult to stop using weight loss medication if they have become accustomed to feeling full on smaller portions.
- MHRA classification: Mounjaro is not classified as an addictive substance by the MHRA and is not a controlled drug.
The concern around "addiction" often reflects the challenge of weight management itself — returning to previous eating patterns after using appetite-suppressing medication can feel difficult, but this is different from true addiction.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
NHS Guidance on Long-Term Mounjaro Use and Stopping
The NHS recognises that long-term use of weight loss medication may be necessary for many people, similar to other chronic disease management treatments like blood pressure medication. NICE guidance on obesity treatment states that medication should be used alongside lifestyle changes, and stopping medication should be planned with your healthcare team.
If you wish to stop Mounjaro, your prescriber should:
- Discuss your reasons for wanting to stop
- Monitor your weight and any return of weight-related health conditions
- Provide support for dietary and activity maintenance
- Plan a timeline that suits your individual circumstances
Stopping Mounjaro suddenly is safe — there is no medical danger — but weight regain often happens relatively quickly without the appetite-suppressing effect and ongoing lifestyle support.
- 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.
Is Mounjaro addictive like painkillers or stimulants?
No. Mounjaro does not activate reward pathways in the brain and is not classified as addictive or controlled by the MHRA. It works on appetite and blood sugar hormones, not dopamine. True addiction involves compulsive use despite harm and withdrawal symptoms — Mounjaro does not cause these.
What happens if I stop taking Mounjaro suddenly?
Stopping is medically safe — there are no dangerous withdrawal symptoms. However, hunger and appetite typically return within days, and weight regain often follows without continued lifestyle changes. Plan stopping with your GP rather than stopping abruptly without support.
Can I become tolerant to Mounjaro over time?
Some users report that appetite suppression may reduce after months or years of use. This is tolerance, not addiction. Your prescriber may adjust your dose, pause treatment, or discuss alternative approaches if this happens.
Why does stopping Mounjaro feel so difficult emotionally?
Returning to normal eating patterns after using appetite-suppressing medication can feel challenging because your body is no longer receiving the hormonal signal to feel full. This difficulty reflects the challenge of weight management itself, not true addiction. Support from your healthcare team can help.
What does the NHS say about long-term Mounjaro use?
The NHS recognises that long-term weight loss medication use is often necessary, similar to managing blood pressure or diabetes. NICE guidance supports ongoing medication use alongside lifestyle changes. Decisions about duration should be made with your GP based on your individual health and weight goals.
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.