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 Online in the UK
Weight loss injections are prescription-only medications available through online prescribing services in the UK, following a clinical assessment. The most commonly prescribed options are Wegovy (semaglutide) and Mounjaro (tirzepatide), both once-weekly GLP-1 receptor agonists approved for weight management. These are not cosmetic treatments — they're legitimate prescription medicines that work by helping regulate appetite and promoting feeling fuller after smaller meals. Access through online prescribers offers an alternative to waiting for NHS weight loss services, though eligibility criteria and clinical assessment requirements still apply. Our BMI calculator can help you understand whether you might be eligible for prescription weight loss treatment.
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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.
How Online Weight Loss Injections Work
Weight loss injections available online in the UK operate through GLP-1 receptor agonist technology, which mimics natural gut hormones that control appetite and blood sugar. When you order through an online prescriber, you'll complete a detailed health questionnaire and have your medical history reviewed by a UK-licensed prescriber before a prescription is issued.
Wegovy (semaglutide) is a once-weekly injection that typically produces weight loss of around 15% of body weight according to clinical trial data, though individual results vary significantly. Doses escalate from 0.25 mg to a maximum of 2.4 mg over several weeks.
Mounjaro (tirzepatide) uses a dual GIP and GLP-1 mechanism — activating two hormone pathways rather than one — and showed average weight loss of 15–21% in clinical trials at maximum dose. Both medications must be combined with reduced-calorie diet and increased physical activity to be effective. Our GLP-1 weight loss calculator can help project potential outcomes at different doses.
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.
Getting Weight Loss Injections Online — What You Need to Know
To obtain weight loss injections online, you must be assessed by a UK-licensed prescriber through a GPhC-registered pharmacy. This is not a case of simply placing an order — genuine online prescribing involves a proper clinical evaluation to check whether you're eligible and whether the medication is safe for you.
Eligibility typically requires: a BMI of 30 or above, or 27–29.9 with weight-related health conditions (type 2 diabetes, high blood pressure, cardiovascular disease, or sleep apnoea). Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may qualify at lower BMI thresholds due to higher health risks at these levels.
Initial prescriptions usually start at the lowest dose and escalate over 4-week intervals. You'll receive injections by post, stored in a refrigerator, and inject yourself once weekly at home. Track your progress using our free progress tracker to monitor weight changes alongside diet and exercise changes.
- 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.
Are weight loss injections available through the NHS online?
NHS access to weight loss injections is through specialist tier 3 weight management services, not online. You'd need a GP referral to these services, which often have long waiting lists. Online prescribing is a private option that doesn't require NHS referral but requires payment. Both routes require clinical assessment — the medication is prescription-only regardless of access route.
How quickly do weight loss injections work when ordered online?
Weight loss typically becomes noticeable after 4–8 weeks on treatment, though this varies. Clinical trials showed average weight loss of 15% over 68 weeks on maximum dose. You won't see overnight results — sustainable weight loss alongside diet and exercise changes takes time. Keeping a food diary and using our progress tracker helps monitor results accurately.
What's the difference between Wegovy and Mounjaro for online prescription?
Both are once-weekly injections available through online prescribers. Wegovy (semaglutide) activates GLP-1 receptors only; Mounjaro (tirzepatide) activates both GIP and GLP-1 receptors. Clinical data suggests Mounjaro may produce slightly greater average weight loss, but individual responses vary. Your prescriber will assess which is more suitable for you based on your health profile.
Can I get weight loss injections online without a prescription?
No. Weight loss injections like Wegovy and Mounjaro are prescription-only medicines in the UK and require a clinical assessment by a licensed prescriber. Any service offering these without a prescription is not legitimate. Always use GPhC-registered pharmacies and UK-licensed prescribers to ensure safety and legality.
Will my GP know if I get weight loss injections from an online prescriber?
Your medical records are confidential, but it's recommended to inform your GP about any prescription medications you're taking, especially GLP-1 injections, as they may interact with other medications or affect existing health conditions. Some GPs are supportive; others may have concerns — transparency is important for your ongoing care.
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.