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
Is Wegovy Safe For Weight Loss in the UK?
Wegovy (semaglutide) is a prescription-only weekly weight loss injection approved for use in the UK by the MHRA. The short answer is: yes, clinical evidence supports Wegovy as safe for weight loss when prescribed by a healthcare professional after proper clinical assessment. The STEP-1 trial showed participants lost an average of 14.9% of their body weight over 68 weeks alongside a reduced-calorie diet and increased physical activity. However, safety depends on individual health circumstances, eligibility criteria, and proper medical supervision through either NHS tier 3 specialist services or private prescribing with a licensed UK prescriber.
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.
NHS Eligibility and Safety Monitoring for Wegovy in the UK
Wegovy eligibility through NHS specialist services requires a BMI of 30 kg/m² or above, or BMI 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds apply (BMI 27.5+). Access is via NHS tier 3 weight management services following GP referral, though waiting lists vary significantly by region.
MHRA safety status: Wegovy is licensed for weight management and subject to standard pharmacovigilance monitoring. The STEP clinical trials demonstrated safety alongside modest gastrointestinal side effects in most users. Common side effects include nausea, diarrhoea, and constipation—typically mild to moderate and often improve over time as the body adjusts.
- Weekly injection dosing (starting 0.25 mg, escalating to 2.4 mg maximum)
- Must be used alongside lifestyle changes, not as standalone treatment
- Regular monitoring recommended, particularly for those with diabetes or cardiovascular conditions
- Not suitable during pregnancy or for those under 18 years of age
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.
NHS vs Private Access: Safety and Prescribing Routes
In the UK, Wegovy access differs between NHS and private routes. NHS route: prescribed through specialist tier 3 services with ongoing clinical monitoring, GP communication, and integration with broader weight management support. Private route: available via online consultation with a GPhC-registered prescriber, with prescription dispensed by registered pharmacies. Both routes require clinical assessment to confirm suitability—private prescribers follow the same safety standards and contraindication checks as NHS services.
Safety considerations apply equally across both routes: individuals with a history of medullary thyroid cancer, multiple endocrine neoplasia type 2 (MEN2), or severe gastroparesis cannot take Wegovy. Those on oral contraceptives should use barrier methods for 4 weeks after starting and after each dose increase, as Wegovy may reduce oral medication absorption. Use our free GLP-1 weight loss calculator to explore potential outcomes, and the BMI calculator to understand your starting point.
- 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 Wegovy safer than other weight loss methods in the UK?
Wegovy is one of several evidence-based approaches to weight management. Clinical trials show it produces modest, sustained weight loss (14.9% average). Safety depends on individual circumstances and medical supervision. Oral medications like orlistat, lifestyle programmes, and bariatric surgery are alternatives—your GP can discuss which is most appropriate for you.
What side effects should I expect with Wegovy?
Very common side effects include nausea, diarrhoea, constipation, and stomach pain, particularly when starting or increasing doses. Most side effects are mild to moderate and often improve over time. Serious side effects (pancreatitis, gallbladder issues, allergic reactions) are rare. Always report persistent or severe symptoms to your prescriber immediately.
Can I get Wegovy on the NHS in my area?
Wegovy is approved by NICE for NHS use through tier 3 specialist weight management services, but availability varies by region and NHS Integrated Care Board. Ask your GP about referral to local services. Waiting lists can be lengthy in some areas. Private online prescribing offers faster access if you meet eligibility criteria.
Is Wegovy safe if I have type 2 diabetes?
Yes, Wegovy can be prescribed to people with type 2 diabetes or prediabetes (both are recognised weight-related conditions). However, if you take insulin or sulphonylureas, your diabetes medication may need adjustment—this requires prescriber oversight. Your GP or specialist will manage this carefully during treatment.
How does Wegovy compare to Mounjaro for safety?
Both are prescription-only, licensed UK weight loss injections with similar safety profiles. Wegovy is a single GLP-1 agonist; Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist. Clinical trials show comparable side effects (nausea, diarrhoea, constipation). Individual tolerability varies. Your prescriber will recommend the most appropriate option based on your health and medical history.
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.