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
Weight Loss Injections — What Are Your UK Options?
If you're considering injections to lose weight in the UK, you have several options available depending on your health needs and circumstances. Weight loss support ranges from free NHS programmes and lifestyle changes right through to prescription medications like Mounjaro and Wegovy. This guide explores the full range of approaches, helping you understand what's available and how to access the right solution for your situation.
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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.
Weight Loss Options Available in the UK
Losing weight safely in the UK involves a structured pathway with options suited to different needs:
- Lifestyle changes (Tier 1): Free support including diet, physical activity, and behavioural coaching through NHS weight management programmes and community groups — the foundation of sustainable weight loss.
- NHS support (Tier 2): Primary care-based weight loss programmes delivered through your GP practice, often digital or group-based interventions.
- Specialist services (Tier 3): Referral to multidisciplinary weight management teams where prescription weight loss medications may be considered alongside intensive lifestyle support.
- Prescription medications: GLP-1 and GIP/GLP-1 receptor agonist injections like Mounjaro (tirzepatide) and Wegovy (semaglutide) — prescription-only, requiring clinical assessment and typically used alongside reduced-calorie diet and increased physical activity.
- Surgical options (Tier 4): Bariatric surgery for severe obesity — referral through NHS specialist services.
Calculate your BMI using our free BMI calculator to understand where you fall on the health weight spectrum and discuss your options with your GP.
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.
How to Choose the Right Approach for You
The most effective weight loss method is one you can sustain long-term. Consider these factors when deciding:
- Starting point: Your current BMI, any weight-related health conditions (diabetes, high blood pressure), and how much weight you need to lose.
- Lifestyle readiness: How much you can commit to dietary changes and increased physical activity — these form the foundation of any approach.
- Medical suitability: Any existing health conditions or medications that might affect which option is right for you.
- NHS vs private access: NHS weight loss medication through specialist services has longer waiting times but lower costs; private online prescribing offers faster access.
Your GP is the best starting point. They can assess your individual circumstances and refer you to appropriate support, whether that's free NHS weight loss programmes or specialist services. Use our free GLP-1 weight loss calculator to estimate potential outcomes with injection-based medication before your appointment.
- 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.
What's the difference between lifestyle changes and weight loss injections?
Lifestyle changes (diet and exercise) are the foundation of sustainable weight loss and work for many people — they're free and available immediately. Weight loss injections are prescription medications that reduce appetite and support feeling fuller, typically used when lifestyle changes alone haven't achieved sufficient results or alongside intensive lifestyle modifications.
Can I get weight loss injections on the NHS?
Yes. Prescription weight loss medications are available through NHS Tier 3 specialist weight management services. You'll need a referral from your GP and meet eligibility criteria (usually BMI 30+, or 27+ with weight-related health conditions). Availability and waiting times vary significantly by region.
How quickly can I access weight loss injections privately?
Private online prescribing through a UK-licensed prescriber can be faster — typically within days to weeks. You'll complete an online health assessment, and if suitable, a prescription is issued to a GPhC-registered pharmacy. Cost starts from approximately £129–£320 per month depending on the medication and dose.
Are weight loss injections safe?
Prescription weight loss injections like Mounjaro and Wegovy have been rigorously tested in clinical trials. They do have side effects (commonly nausea and digestive changes). A prescriber will assess whether they're safe and suitable for your individual health profile before prescribing — always follow medical guidance.
Do weight loss injections work without diet and exercise changes?
Weight loss injections work best alongside a reduced-calorie diet and increased physical activity. Clinical trials show that people who combine medication with lifestyle changes achieve significantly better results than medication alone. Sustainable weight loss UK requires both support and personal commitment.
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.