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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Why Isn't Your 7.5 mg Mounjaro Working?
If you're on a 7.5 mg Mounjaro dose and not seeing the weight loss results you expected, you're not alone — individual responses vary significantly, and several factors affect how well this tirzepatide injection works for you. This guide explains what might be happening, how long to expect results, and your options for accessing Mounjaro in the UK, whether through NHS specialist services or private online prescription routes. Understanding the cost, eligibility, and realistic timelines can help you make informed decisions about your weight management journey.
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Calculate Your BMI Instantly
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.
Understanding Mounjaro Effectiveness & Access Routes
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — a different mechanism to Wegovy (semaglutide), which may mean different results for different people. Clinical trials showed average weight loss of around 15–21% body weight over 72 weeks, but individual outcomes vary considerably based on diet adherence, physical activity, genetics, and underlying health conditions.
Why 7.5 mg might feel ineffective:
- You may still be in the dose titration phase — moving from 5 mg to 7.5 mg requires at least 4 weeks at each dose before increasing further (maximum dose is 15 mg)
- Diet and exercise adherence significantly impacts results — Mounjaro works best alongside a reduced-calorie diet and increased physical activity
- Some people respond better to higher doses; your prescriber may recommend escalating to 10 mg or 15 mg
- Underlying conditions like PCOS, thyroid dysfunction, or certain medications can affect weight loss response
- Tolerance can develop over time, though this is less common than with some other medications
In the UK, access to Mounjaro is available through NHS tier 3 specialist weight management services (subject to local commissioning and waiting lists) or via private prescription through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber. Use our free GLP-1 weight loss calculator to explore projected outcomes at different doses.
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.
Cost, NHS Eligibility & Private Prescription Process
NHS route: Mounjaro is approved by NICE for specialist weight management services in eligible adults. Access requires GP referral to your local tier 3 weight management service. Availability varies significantly by region and waiting lists can be several months. You must meet eligibility criteria: BMI ≥30 (or ≥27.5 for South Asian, Chinese, Black African, or Black Caribbean adults with weight-related health conditions).
Private prescription costs: Without mentioning specific pharmacy prices, private Mounjaro prescriptions in the UK typically range from £150–£300+ per month depending on dose, with higher doses (like 7.5 mg) at the upper end. This includes the prescription fee and medication supply. Online consultations are usually £20–£50.
What to expect: Complete an online health questionnaire, consult with a prescriber, receive a prescription if approved, and your medication is dispensed by a registered pharmacy. Always discuss with your prescriber whether increasing your dose, optimising diet and exercise, or exploring alternative medications like Wegovy might be more appropriate for your situation.
- 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 7.5 mg to work?
Most people need at least 4–8 weeks at a stable dose to see meaningful results. Weight loss often accelerates after 12–16 weeks as the body adjusts. If you've been on 7.5 mg for less than 4 weeks, you may still be in the adjustment phase. Discuss with your prescriber about further dose escalation or lifestyle optimisation.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP+GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials showed Mounjaro achieved slightly higher average weight loss, but individual responses vary. Some people respond better to one than the other. Your prescriber can advise which is more suitable.
Can I get Mounjaro on the NHS in the UK?
Yes, Mounjaro is approved by NICE for NHS specialist weight management services. You need a GP referral to your local tier 3 service and must meet eligibility criteria (BMI ≥30 or ≥27.5 with comorbidities). Waiting times and availability vary by region. Private prescription is available without NHS referral through online pharmacies.
What should I do if Mounjaro 7.5 mg isn't working?
First, review your diet and physical activity — Mounjaro works best alongside a reduced-calorie diet. Second, discuss with your prescriber whether increasing to 10 mg or 15 mg is appropriate. Third, ensure you've been on 7.5 mg for at least 4 weeks before judging effectiveness. Your prescriber may also suggest exploring alternative medications or investigating underlying health factors.
How much does a private Mounjaro prescription cost in the UK?
Private Mounjaro typically costs £150–£300+ per month depending on dose and provider, plus an online consultation fee (usually £20–£50). Costs are higher for higher doses like 7.5 mg. Check directly with GPhC-registered pharmacies for current pricing. NHS access is free but involves waiting lists and regional variation.
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.