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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Private Weight Loss Injections in the UK
Private weight loss injections are prescription-only medications available through online clinics and private prescribers in the UK. These GLP-1 and dual GIP/GLP-1 receptor agonist medications have shown promising results in clinical trials for weight management. If you're considering private weight loss medication, it's important to understand your options, eligibility criteria, and how they compare to NHS access. This guide covers the three main prescription injections available privately in the UK and what you need to know before starting treatment.
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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.
UK-Licensed Weight Loss Injections Available Privately
Three prescription-only weight loss injections are currently licensed in the UK and available through private prescribing:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist, administered once weekly. Maximum dose is 15 mg. In clinical trials, participants lost an average of 15–21% of their body weight over 72 weeks alongside diet and exercise changes.
- Wegovy (semaglutide) — a GLP-1 receptor agonist, administered once weekly. Maximum dose is 2.4 mg. Clinical trial data showed average weight loss of approximately 15% of body weight at the highest dose.
- Saxenda (liraglutide) — a GLP-1 receptor agonist, administered as a daily injection. Maximum dose is 3 mg daily. Results are similar to Wegovy, with average weight loss of around 5–10% of body weight in trials.
All three medications require a prescription from a UK-licensed prescriber and are most effective when combined with reduced-calorie diet and increased physical activity. Individual results vary significantly.
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 — How to Choose
You can access weight loss injections through two routes in the UK. NHS access is available through specialist tier 3 weight management services, but eligibility is restricted and waiting times are often lengthy. Private access requires an online clinical assessment with a UK-licensed prescriber; if approved, the prescription is dispensed by a registered pharmacy. Private treatment typically costs £129–£320 per month depending on dose and provider. Before pursuing private treatment, speak to your GP about whether you might be eligible for NHS specialist services. Your GP can also advise whether prescription weight loss medication is appropriate for your individual health circumstances.
- 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.
Who is eligible for private weight loss injections in the UK?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or heart disease. Lower thresholds apply for people of South Asian, Chinese, Black African, or Black Caribbean heritage due to increased health risks at lower BMI levels. A licensed prescriber will assess your individual eligibility during a clinical consultation.
Are private weight loss injections safe?
These medications are prescription-only and licensed by the MHRA for weight management. Like all medicines, they carry potential side effects — most commonly nausea, diarrhoea, constipation, and vomiting. Serious side effects are rare. A prescriber will review your medical history and current medications before approving treatment to ensure safety. Always report any concerns to your healthcare provider.
How quickly will I lose weight on a private weight loss injection?
Weight loss varies significantly between individuals and depends on dose, diet, and exercise. Clinical trials showed average weight loss of 15–21% over several months, but this is not assured. Most people see gradual weight loss over weeks and months as their dose is increased. Your progress can be tracked using our free progress tracker to monitor changes alongside other measurements like BMI.
Can I get weight loss injections through the NHS?
Yes — weight loss injections are available through NHS specialist tier 3 weight management services for eligible adults. However, NHS availability varies significantly by region, and waiting lists can be very long. Your GP can refer you to your local service, but private access is often faster. Speak to your GP about which route is best for you.
What happens when I stop taking the injection?
Weight loss medication is typically intended for long-term use. If you stop taking it, appetite-regulating hormones gradually return to baseline, and weight may be gradually regained if lifestyle changes are not maintained. Successful weight management combines medication with sustained diet and exercise changes. Discuss long-term plans with your prescriber.
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.