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
How Long Should You Stay On Mounjaro?
Most people taking Mounjaro (tirzepatide) continue treatment for as long as it's helping them manage their weight and it remains safe to use. There's no fixed "end date" — treatment duration is individualised based on your response, health goals, and how well you tolerate the medication. In the UK, access to Mounjaro is available through NHS specialist weight management services or private prescription following an online clinical assessment. Understanding both the timeline of treatment and how to access it can help you make an informed decision about whether this medication 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 Long Do People Stay On Mounjaro?
Treatment duration varies significantly between individuals. Some people may see meaningful weight loss within 12–16 weeks, whilst others take longer to respond. Most clinical guidance suggests continuing Mounjaro for at least 6–12 months to assess effectiveness properly. If you're losing weight and tolerating the medication well, your prescriber may recommend continuing beyond this timeframe.
Important considerations for treatment length include:
- Weight loss typically plateaus after 12–18 months on a stable dose
- Some people continue indefinitely if weight regain occurs when stopping
- If you experience intolerable side effects, your prescriber may reduce the dose or discontinue treatment
- The Mounjaro KwikPen is a once-weekly injection, requiring ongoing commitment to injections
- Dose titration happens gradually — reaching your maintenance dose takes 4–5 months
Your prescriber will monitor your progress and discuss continuing, adjusting, or stopping treatment based on your individual response and health status. Weight loss is typically most significant in the first 12 months, after which the rate of loss often slows.
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.
Mounjaro Cost & UK Access Routes
In the UK, Mounjaro access differs depending on your route: NHS access is through specialist tier 3 weight management services, usually via GP referral, though availability and waiting times vary significantly by region. Private prescription costs range from approximately £150–£280 per month depending on dose and provider, with doses starting at 2.5 mg and escalating weekly to a maximum of 15 mg.
Private access involves an online consultation with a UK-licensed prescriber, who assesses your eligibility based on BMI, health conditions, and medical history. If approved, your prescription is dispensed by a GPhC-registered pharmacy. NHS eligibility follows NICE guidance for adults with BMI ≥30 or BMI 27–29.9 with weight-related conditions. Many people combine treatment with our free GLP-1 weight loss calculator to project outcomes and track progress using our progress tracker.
- 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 to see results on Mounjaro?
Most people notice appetite reduction within 1–2 weeks of starting, but measurable weight loss typically becomes apparent after 4–8 weeks. Significant weight loss is usually observed by 12–16 weeks. Individual results vary depending on diet, activity level, and starting dose. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks when combined with lifestyle changes.
Can you stop Mounjaro after losing weight?
Yes, you can stop Mounjaro at any time if you and your prescriber decide it's appropriate. However, weight regain often occurs when stopping the medication because appetite hormones return to baseline levels. Some people choose to continue at a lower maintenance dose long-term to prevent weight regain. Your prescriber will discuss the pros and cons of stopping based on your individual situation.
Is Mounjaro available on the NHS in the UK?
Yes, Mounjaro (tirzepatide) has been approved by NICE for use within NHS specialist weight management services. However, NHS access involves referral to tier 3 services, eligibility assessment, and often significant waiting times — availability varies greatly by region and local health boards. Private prescription is an alternative route if NHS waiting times are prohibitive.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £150–£280 per month depending on your dose (2.5 mg to 15 mg) and the provider. A full month's supply contains four weekly injections. You'll also pay for the online consultation fee (usually £20–£50). Total first-month cost is typically £170–£330. Compare this cost against NHS waiting lists when deciding your access route.
What happens if Mounjaro side effects become unbearable?
If you experience severe side effects, inform your prescriber immediately. Options include reducing your dose, pausing treatment for a week or two, or stopping completely. Common initial side effects (nausea, diarrhoea) often improve over 1–2 weeks as your body adjusts. Serious side effects like severe stomach pain warrant urgent medical attention and likely discontinuation.
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.