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 Expect On 5mg Mounjaro
The 5mg dose of Mounjaro (tirzepatide) is typically the first maintenance dose after the initial 2.5mg starter weeks. At this dose, you may begin to notice more noticeable effects on appetite and fullness, though individual responses vary considerably. This guide covers what people commonly experience on 5mg, typical side effects, expected weight loss timelines, and practical advice for managing this dose. Remember that everyone's experience is unique, and your GP or prescriber should monitor your response.
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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.
What Happens At 5mg Mounjaro — Timeline And Effects
Weeks 1–2 on 5mg: Most people notice stronger appetite reduction compared to the 2.5mg starter dose. You may feel fuller after smaller meals, experience reduced cravings, or find food less appealing than before. Some users report a slight "metallic" taste or mild stomach adjustments during this transition.
Weeks 3–4 on 5mg: Effects typically stabilise. Appetite suppression becomes more consistent. If you're following a reduced-calorie diet alongside the injection, weight loss may become visible on scales — though the dose titration schedule (minimum 4 weeks at 5mg before increasing) means you may not yet be at your target dose for maximum effect.
Expected weight loss at 5mg: Based on clinical trial data, 5mg is a lower maintenance dose. Average weight loss across SURMOUNT-1 trial participants at the 5mg dose was approximately 15% of body weight over 72 weeks when combined with diet and physical activity. This translates to roughly 0.25–0.5kg per week, though results vary significantly. Use our free GLP-1 weight loss calculator to estimate your potential weight loss at this dose.
- Gastrointestinal effects (nausea, constipation, diarrhoea) usually peak in week 1–2 at each dose and often improve as your body adjusts
- Appetite suppression typically strengthens as the dose increases
- Weight loss is gradual — expect visible changes after 4–6 weeks
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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.
Common Side Effects And Managing 5mg Mounjaro
Nausea is the most frequently reported side effect at 5mg, affecting many users in the first 1–2 weeks. Strategies to manage this include eating smaller, frequent meals; avoiding fatty or greasy foods; staying hydrated; and taking anti-nausea medication if prescribed by your GP. Constipation and diarrhoea are also common — increasing fibre intake, hydration, and physical activity can help.
Less common but important: Some people experience fatigue, headache, or reduced appetite so severe they struggle to eat enough calories — contact your prescriber if this occurs. Injection site reactions (redness, bruising, mild pain) are normal and typically resolve within days. Store your Mounjaro KwikPen correctly (2–8°C unopened) and rotate injection sites weekly to minimise these.
If side effects become severe or persistent after 2 weeks, inform your GP or prescriber — dose adjustment or additional support may be needed before escalating to the next dose.
- 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.
Is 5mg Mounjaro a high dose?
No. 5mg is the first maintenance dose — you start at 2.5mg for 4 weeks, then move to 5mg. Maximum dose is 15mg. Many people eventually escalate to 10mg, 12.5mg, or 15mg for stronger appetite suppression and greater weight loss. 5mg is considered a moderate starting maintenance dose.
How much weight will I lose on 5mg Mounjaro?
Clinical trials showed average weight loss of approximately 15% body weight at 5mg over 72 weeks, alongside diet and exercise. However, individual results vary considerably. Use our GLP-1 weight loss calculator above to estimate your potential loss. Your own weight loss depends on your starting weight, calorie deficit, activity level, and how your body responds to tirzepatide.
When can I increase from 5mg to a higher Mounjaro dose?
You must remain on 5mg for a minimum of 4 weeks before your prescriber will consider escalation. After 4 weeks, if you're tolerating the dose well and your weight loss is progressing, your prescriber may increase you to 7.5mg. Dose escalation decisions are based on individual response, side effects, and health goals.
What's the difference between 5mg Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist. Wegovy (semaglutide) is a GLP-1 agonist only. In clinical trials, 5mg Mounjaro showed approximately 15% average weight loss, while Wegovy showed similar results. Both are prescription-only and require clinical assessment. Your prescriber will assess which is more suitable for you.
Can I stay on 5mg Mounjaro long-term?
Yes, many people remain on stable doses long-term if they're achieving their weight loss goals and tolerating side effects well. However, dose escalation to 10mg or higher may provide better results. This is a personal decision made with your prescriber based on your response, health goals, and any comorbidities. Regular GP monitoring is recommended.
Ready to take control of your weight loss journey?
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