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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Only Losing 1lb A Week On Mounjaro — What You Should Know
If you're only losing 1lb (approximately 0.45kg) per week on Mounjaro, you may be wondering if this is normal or whether your dose needs adjusting. The truth is that weight loss on Mounjaro varies significantly between individuals — what's considered "slow" for one person may be perfectly healthy progress for another. This guide explains what influences your weight loss rate, when slower progress is still meaningful, and what to discuss with your prescriber.
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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.
Why Weight Loss Varies On Mounjaro
Mounjaro (tirzepatide) is a prescription-only dual GIP and GLP-1 receptor agonist that may help support weight loss alongside a reduced-calorie diet and increased physical activity. However, individual results vary considerably, and losing 1lb per week is actually within a healthy weight loss range according to NHS guidance.
Several factors influence how quickly you lose weight on Mounjaro:
- Starting weight: People with higher starting weights often lose weight faster initially
- Current dose: You may still be titrating up through doses (2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg) — weight loss typically increases as you reach higher maintenance doses
- Metabolism: Individual metabolic rates vary based on age, genetics, muscle mass, and medical history
- Adherence to diet and exercise: Mounjaro works best alongside a reduced-calorie diet and physical activity
- Other medications: Certain medications or medical conditions may affect weight loss rate
- Body composition: If you're building muscle while losing fat, the scales may not reflect your actual progress
Clinical trials showed that participants on Mounjaro lost an average of 15–21% of body weight over 72 weeks, but this masks a wide range of individual outcomes — some lost more, some lost less.
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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.
Is 1lb Per Week A Good Rate Of Weight Loss?
Yes, 1lb per week is considered healthy and sustainable weight loss by NHS standards. The NHS recommends losing 0.5–1kg (roughly 1–2lbs) per week for sustainable, long-term results. At 1lb weekly, you're hitting the lower end of this range, which is actually ideal because it minimises muscle loss and supports metabolic health.
Faster weight loss isn't always better — very rapid loss (more than 2lbs per week) can lead to muscle breakdown, nutritional deficiency, and metabolic adaptation. Use our free progress tracker to log your weekly weight and see your trend over 4–8 weeks rather than focusing on single-week fluctuations. If you're consistently losing 1lb weekly alongside improved energy, better blood sugar control, or reduced appetite, this indicates Mounjaro is working effectively for you. Discuss your individual targets and rate of loss with your prescriber during your regular reviews.
- 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.
Should I ask my prescriber to increase my Mounjaro dose if I'm only losing 1lb a week?
Not necessarily. Losing 1lb weekly is within NHS recommended safe limits. Your prescriber will review your progress at each appointment and adjust your dose based on your overall health, how well you're tolerating Mounjaro, and your individual response. They may increase your dose if you're not yet at the maximum (15mg) and your tolerability allows. Never increase your dose yourself — always follow your prescriber's guidance.
How long should I expect to stay at each Mounjaro dose before seeing results?
You should remain on each dose for a minimum of 4 weeks before your prescriber considers increasing it. Weight loss is typically more noticeable as you move from 5mg through to 10mg and 15mg doses. If you're still in the early titration phase (weeks 1–12), your appetite suppression and weight loss may increase as you progress to higher doses. Your prescriber will assess your progress and tolerability at each step.
Does Mounjaro work better if combined with specific diet approaches?
Mounjaro works best alongside a reduced-calorie diet and regular physical activity — this is how it was used in clinical trials. The type of diet (Mediterranean, low-carb, calorie counting) matters less than adherence and achieving a calorie deficit. Many people find Mounjaro makes it easier to stick to a diet because appetite suppression reduces cravings. Your GP or a dietitian can advise on a sustainable approach that suits your lifestyle.
What's the difference between Mounjaro and Wegovy for weight loss rate?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials showed Mounjaro may produce slightly greater average weight loss (~20.9% at 15mg) compared to Wegovy (~14.9% at 2.4mg), but individual results vary widely and both are prescription-only medications requiring clinical assessment.
Should I be concerned if my weight loss plateaus after a few weeks?
Weight loss plateaus are normal and don't mean Mounjaro has stopped working. Plateaus often happen because your body adapts to a lower weight, or because your calorie intake has gradually increased. Small dietary adjustments, increased physical activity, or waiting for your next dose increase can help break a plateau. Use our free BMI calculator to check your BMI progress alongside weight — body composition changes may not always show on the scales immediately.
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.