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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What to Do If Mounjaro Isn't Working at 7.5mg
If you've been taking 7.5mg Mounjaro (tirzepatide) and haven't seen expected weight loss results, you're not alone — individual responses vary significantly. The 7.5mg dose is typically an intermediate step during dose titration, not the final maintenance dose. Your prescriber may need to assess whether to increase to 10mg, continue at 7.5mg with lifestyle adjustments, or review whether the medication is suitable for you. This guide explains what "not working" might mean, when dose increases are appropriate, and how to get the right support through the NHS or private prescribing routes in the UK.
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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 Response and Dose Titration
Mounjaro works differently for different people, and weight loss at each dose level varies considerably. At 7.5mg, you're typically in the dose escalation phase — clinical trials showed average weight loss of around 15–19% body weight on this dose, but individual results ranged from minimal loss to significant loss depending on adherence, lifestyle factors, and personal metabolism.
Common reasons Mounjaro may seem ineffective:
- Insufficient time at the dose — weight loss can take 4–8 weeks to become noticeable at each dose level
- Dietary intake exceeding the calorie deficit needed for loss — the medication reduces appetite but doesn't prevent overeating if intake remains high
- Underlying medical conditions affecting weight — thyroid dysfunction, PCOS, or metabolic issues require specialist assessment
- Medication interactions — some medications affect how tirzepatide works or how quickly food moves through your digestive system
- Expectation mismatch — average loss is 15–21% body weight, but this takes months, not weeks
The 7.5mg dose is designed as a stepping stone — your prescriber will typically plan to increase to 10mg after 4 weeks on 7.5mg if you're tolerating it well. Staying on 7.5mg longer than the planned titration schedule may result in a plateau in 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.
Next Steps: Dose Adjustment and NHS Support
If you've been on 7.5mg for at least 4 weeks with no side effects, ask your prescriber about increasing to 10mg as planned. If you're experiencing significant side effects (severe nausea, vomiting, or stomach pain), discuss whether to stay on 7.5mg longer or switch medications.
On the NHS, you'll be supported through a tier 3 specialist weight management service — your prescriber will review your progress at each dose and adjust the plan based on your individual response. Privately, your online prescriber will assess your progress and manage dose changes. Either route, combination of diet, physical activity, and the medication is essential for results — Mounjaro supports weight loss but doesn't replace the need for lifestyle change. Track your progress using our free progress tracker to identify patterns beyond just the scale.
- 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.
Why isn't my 7.5mg Mounjaro helping me lose weight?
Weight loss takes time — most people see noticeable results between 4–8 weeks at each dose level. At 7.5mg, average loss is 15–19% body weight, but individual results vary. If you've been on 7.5mg for less than 4 weeks, give it more time. If it's been longer with no progress, discuss dose increase to 10mg or lifestyle review with your prescriber. Ensure your diet supports a calorie deficit — the medication reduces appetite but doesn't prevent overeating.
Should I stay on 7.5mg longer or move to 10mg?
The standard Mounjaro titration plan increases the dose every 4 weeks if tolerated well. If you've been on 7.5mg for 4+ weeks without severe side effects and your prescriber agrees you're ready, moving to 10mg is typical. This higher dose produced average weight loss of around 19.5% in clinical trials. Discuss your individual progress with your prescriber — they may recommend staying longer if side effects are still adjusting, or switching approaches if 7.5mg clearly isn't suitable.
Could a medical condition be preventing weight loss on Mounjaro?
Yes. Underactive thyroid, PCOS, cortisol imbalance, and certain medications can slow or prevent weight loss even on Mounjaro. If you've been on adequate doses for 3+ months with minimal progress despite diet and activity changes, ask your GP for blood tests — thyroid function, glucose, and metabolic markers. Some conditions require specialist treatment alongside GLP-1 medication for effective weight management.
What's the difference between 7.5mg and 10mg Mounjaro?
Clinical trials showed approximately 19.5% average body weight loss on 10mg versus 15–19% on 7.5mg. The higher dose typically increases side effects slightly (nausea, diarrhoea) but often produces better weight loss results. Your prescriber will evaluate whether moving up is appropriate based on your tolerance and progress. Not everyone needs to reach 15mg — some people achieve their goals on 10mg.
Should I use the NHS or private route if Mounjaro isn't working?
Both routes support dose adjustment and monitoring. NHS specialist tier 3 services assess you comprehensively and manage escalation, but waiting lists vary by region (sometimes months). Private online prescribing is faster and more flexible but requires upfront cost (typically £129–£320/month). Either way, your prescriber will review your progress at 4-week intervals and adjust your dose or plan based on results — the key is consistent follow-up.
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.