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
Average Weight Loss on Mounjaro 2.5 mg — What to Expect
Mounjaro (tirzepatide) is started at a 2.5 mg dose, which is the initial adjustment phase before escalating to higher maintenance doses. Most people taking Mounjaro 2.5 mg do not yet experience significant weight loss at this early stage — the dose is designed to allow your body to adjust to the medication. Weight loss acceleration typically begins at 5 mg and above. Understanding where your current weight falls within NHS healthy weight ranges and using a BMI calculator can help you set realistic expectations for your weight loss journey with Mounjaro.
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.
Healthy Weight Range and BMI Context for Your Height
Before considering any weight loss medication, it's important to understand what constitutes a healthy weight range for your height. According to NHS guidelines, a healthy BMI sits between 18.5 and 24.9. This translates to different weight ranges depending on your height.
For example, if you're 5ft 8in (173 cm) tall, the healthy weight range is approximately 55–74 kg (8st 8lbs to 11st 8lbs). If you're 5ft 4in (163 cm) tall, the healthy weight range is roughly 49–66 kg (7st 10lbs to 10st 6lbs). For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds — a healthy BMI starts at 18.5 but overweight begins at 23, reflecting higher health risks at lower weights.
Use our free BMI calculator above to find your personal healthy weight range instantly, based on your exact height and ethnic background. This helps you understand what an ideal body weight looks like for you, rather than focusing solely on average UK weight figures.
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 2.5 mg: Starting Dose Weight Loss Reality
At 2.5 mg, Mounjaro is not designed for significant weight loss. This is the starting or adjustment dose — your body is adapting to the medication's effects. Clinical trial data shows that meaningful weight loss (typically 15–21% of body weight) occurs at higher doses: 5 mg, 10 mg, or 15 mg.
However, some people report modest changes in appetite or initial weight reduction of 1–2 kg in the first few weeks at 2.5 mg. Results vary significantly between individuals. Your prescriber will increase your dose every 4 weeks if tolerated, moving you towards maintenance doses where weight loss acceleration becomes more noticeable. Track your progress using our free progress tracker to monitor changes over several weeks, rather than expecting rapid results immediately. Your GP or prescriber should review your progress at each dose escalation.
- 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 much weight do people lose on Mounjaro 2.5 mg in the first month?
At 2.5 mg, weight loss is typically minimal — many people report 0–2 kg loss in the first 4 weeks. This dose is designed for adjustment, not significant weight loss. Weight loss acceleration usually begins once you reach 5 mg or higher, after 4–8 weeks of treatment. Individual results vary considerably based on diet, activity, and metabolism.
Is Mounjaro 2.5 mg the right dose if I want to lose weight?
No — 2.5 mg is the starting dose only. Your prescriber will increase it every 4 weeks if tolerated. Most weight loss occurs at 5 mg and above. The 2.5 mg phase allows your body to adjust and helps your prescriber assess how you tolerate the medication before moving to higher, more effective doses.
How does my healthy weight range relate to starting Mounjaro?
Your healthy weight range (based on BMI 18.5–24.9 for your height) is your target. Mounjaro helps you move towards this range if you're currently above it. Use our free BMI calculator to find your personal healthy weight range, then discuss realistic timelines with your prescriber. Weight loss is gradual and individual.
Can I calculate my ideal body weight before starting Mounjaro?
Yes. Calculate your BMI and healthy weight range using our free BMI calculator above — it shows you the target weight range for your exact height. For adults of South Asian or Black African heritage, lower BMI thresholds apply. Your GP can discuss whether Mounjaro is appropriate to help you reach this range.
What if I don't lose weight on Mounjaro 2.5 mg — should I worry?
Not necessarily. 2.5 mg is a starting dose; significant weight loss typically doesn't occur until doses increase to 5 mg and above. Some side effects (like nausea or reduced appetite) may actually support weight loss before you notice it on the scales. Track changes weekly using our progress tracker, and discuss any concerns with your prescriber at your dose review.
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.