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
Why 7.5 mg Mounjaro Might Not Be Working for You
If you've been on 7.5 mg Mounjaro and aren't seeing the weight loss results you expected, you're not alone — individual responses vary significantly. This page explains why tirzepatide may not be delivering results for you, what to expect during dose titration, and when to contact your prescriber. Understanding the clinical context and NHS guidance can help you make informed decisions about your treatment. Remember, weight loss medication works best alongside dietary changes and increased physical activity.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Why Mounjaro May Not Be Working Yet
There are several reasons why 7.5 mg Mounjaro may not be delivering visible weight loss yet, and none necessarily mean the medication is inappropriate for you:
- You may still be in the dose titration phase — your prescriber gradually increases your Mounjaro dose every 4 weeks. At 7.5 mg, you're at an intermediate dose; some people don't see significant results until reaching 10 mg or higher
- Individual response varies — clinical trials show average weight loss of around 15–21% over 72 weeks, but individual results range from minimal loss to substantial reductions. Genetics, metabolism, underlying health conditions, and adherence to lifestyle changes all influence outcomes
- Timeline matters — meaningful weight loss typically becomes noticeable after 8–12 weeks at a stable dose. If you've been at 7.5 mg for fewer than 4 weeks, your body may still be adjusting
- Lifestyle factors — Mounjaro is not a standalone treatment. Without a reduced-calorie diet and increased physical activity, weight loss will be minimal or absent. Your prescriber should have discussed this at initiation
- Medical factors — certain medications (including some diabetes treatments), hormonal conditions like hypothyroidism, and polycystic ovary syndrome (PCOS) can reduce weight loss results
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.
What to Do If Mounjaro Isn't Working
If you've been on 7.5 mg for at least 4 weeks and have made sustained dietary and exercise changes without seeing any progress, contact your prescriber. They will review your: adherence to injections, dietary intake, physical activity level, current medications, and any underlying health conditions that might be limiting results.
Your prescriber may recommend: continuing to the next scheduled dose increase (10 mg), extending your time at 7.5 mg, investigating underlying medical causes, or in some cases, pausing treatment to reassess suitability. Through NHS specialist tier 3 services, this review is included as part of your ongoing care. Privately, ensure your prescriber offers follow-up 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.
How long should I wait before deciding Mounjaro isn't working?
Minimum 8–12 weeks at your current stable dose alongside consistent lifestyle changes. During dose titration (every 4 weeks), results may be gradual. If no weight loss after 12 weeks at the same dose with full adherence and lifestyle changes, contact your prescriber for a review.
Is 7.5 mg Mounjaro a common dose to stay on long-term?
7.5 mg is typically an intermediate dose during titration towards the maximum 15 mg. Some people achieve their weight loss goals at 7.5 mg and remain stable. Others require dose escalation to 10 mg, 12.5 mg, or 15 mg for better results.
Can I switch from Mounjaro to Wegovy if Mounjaro isn't working?
This is a decision between you and your prescriber. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is GLP-1 only. Some people respond better to one than the other, but any switch requires clinical assessment and must be managed by your prescriber.
Does the Mounjaro KwikPen device affect how well the medication works?
The KwikPen is designed to deliver the correct dose reliably. Injection technique, storage (2–8°C before first use, below 30°C after), and ensuring you complete the full injection can affect efficacy. Your prescriber should have shown you proper injection technique.
What if I'm following diet and exercise advice but still not losing weight on 7.5 mg?
Medical factors such as hypothyroidism, PCOS, hormonal imbalances, or certain medications can limit weight loss despite treatment. Your GP can arrange blood tests to check your thyroid function and other relevant markers if you haven't had recent investigations.
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.