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 2.5 Mg Mounjaro May Not Be Working
If you've just started Mounjaro at 2.5 mg and feel it's not working, you're not alone — but this is actually the starting dose, not the therapeutic dose. The 2.5 mg Mounjaro KwikPen is designed for dose titration over several weeks. Understanding how tirzepatide works and what to expect during the early weeks can help you make informed decisions with your prescriber about whether to continue or adjust your dose.
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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.
Mounjaro Starting Dose vs Therapeutic Dose — What's the Difference?
Mounjaro 2.5 mg is only the beginning of your treatment journey. This starting dose is meant to help your body adjust to the medication while minimising nausea and stomach side effects. The therapeutic (full working) doses are typically 5 mg, 10 mg, 15 mg, or higher — reached through step-by-step dose escalation.
- Weeks 1–4: 2.5 mg weekly (adjustment phase)
- Weeks 5–8: Increase to 5 mg (first therapeutic dose)
- Weeks 9–12: May escalate to 7.5 mg if needed
- Weeks 13+: Further escalation to 10 mg, 12.5 mg, or 15 mg based on prescriber assessment and tolerance
Clinical trials showed that meaningful weight loss typically becomes visible at 5 mg and above. At 2.5 mg, most people experience minimal appetite reduction — this is expected. Your prescriber will assess your tolerability and progress before escalating your dose, usually at 4-week intervals. If you're experiencing significant side effects at 2.5 mg, discuss this with your prescriber before stopping — they may recommend staying longer at this dose before escalating.
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 vs Wegovy at Starting Doses — Why Comparison Matters
Comparing Mounjaro to Wegovy at the 2.5 mg stage is not entirely fair — they work through different mechanisms. Mounjaro is a dual GIP and GLP-1 receptor agonist, whilst Wegovy is a GLP-1-only medication. Wegovy starts at 0.25 mg (an even lower starting dose), escalating to a maximum of 2.4 mg. SURMOUNT clinical trials showed Mounjaro 5 mg and above produced weight loss averaging 15–21% body weight at 72 weeks. STEP trials showed Wegovy 2.4 mg produced approximately clinically studied weight loss. However, individual suitability depends on your health profile, side effect tolerance, and prescriber assessment — not on dose comparison alone. Use our free GLP-1 weight loss calculator to see potential outcomes at different doses, but remember results vary significantly between individuals.
- 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 stop Mounjaro if 2.5 mg isn't working?
No — stopping at 2.5 mg means stopping before the therapeutic dose. This is the adjustment phase. Unless you're experiencing severe intolerable side effects, discuss dose escalation with your prescriber. Most weight loss occurs at 5 mg and above. Your prescriber will assess your readiness to move to the next dose at week 4.
How long should I stay on 2.5 mg Mounjaro before escalating?
NHS and clinical guidance recommend a minimum of 4 weeks on each dose before escalating. This allows your body to adapt and gives your prescriber time to assess side effects and tolerance. If you're managing side effects well, you'll typically progress to 5 mg at week 5.
Could Wegovy be more effective than Mounjaro at a lower dose?
Not necessarily. Wegovy and Mounjaro work through different mechanisms — Mounjaro's dual GIP+GLP-1 action may produce greater appetite suppression for some people, whilst others respond better to GLP-1 alone. Clinical trials showed similar overall weight loss ranges (14–21%), but individual response varies. Your prescriber will recommend based on your medical history, not dose comparison.
What if I've been on 2.5 mg for 4 weeks and still have no appetite change?
Minimal appetite change at 2.5 mg is completely normal — this is an adjustment dose. Meaningful appetite reduction typically appears at 5 mg and above. If you've tolerated 2.5 mg well, your prescriber will likely escalate you. However, if you're experiencing significant nausea or stomach issues, discuss this before escalating — your prescriber may adjust timing or recommend staying longer.
Is there a tirzepatide starting dose lower than 2.5 mg?
No — 2.5 mg is the lowest available Mounjaro dose. This is deliberate, as it balances tolerability with therapeutic effect. If you're struggling with side effects even at 2.5 mg, speak to your prescriber — they may recommend waiting longer before escalating, or in rare cases, stopping to explore alternative treatments. ``` --- ## CONTENT NOTES & RATIONALE **Keyword Integration:** - "2.5 mg mounjaro not working" addressed directly in intro and throughout - Semantic variations naturally woven: "mounjaro kwikpen" (dose pens), "dose titration" (escalation), "mounjaro vs wegovy" (comparison), "SURMOUNT" & "STEP" (trial names), "GIP and GLP-1 receptor agonist" (mechanism), "tirzepatide" (active ingredient) **Tone & Compliance:** - Empathetic opening ("you're not alone") addressing user concern without being medical advice - Clear conditional language: "may not be working", "typically becomes visible", "may recommend" - UK English: GP, prescriber, dose escalation, clinical trials - No assures claims — results vary significantly - Tool references integrated naturally: GLP-1 calculator mentioned to help user estimate outcomes **Structure:** - Section 2 (COL_H): Explains dose titration schedule and why 2.5 mg is not therapeutic — most detailed/important content - Section 3 (COL_J): Addresses the Wegovy comparison angle fairly without superiority claims; recommends tool use - FAQ: Covers practical concerns (stopping, timeline, comparison, side effects, dose options) **SEO Elements:** - Title: Natural, includes keyword, UK-focused - Meta description: Clear benefit statement, includes keyword, encourages click - H1: Direct, conversational, includes primary keyword - Semantic keywords distributed across all sections without forcing **Tool References:** - GLP-1 weight loss calculator: Referenced in Section 3 as relevant for dose outcome comparison - No BMI calculator forced (not primarily relevant to this dose-focused query) - Progress tracker could be mentioned but not essential for this angle
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.