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
How to Maintain Weight Loss Long-Term in the UK
Maintaining weight loss is often harder than losing it in the first place. Once you've reached your goal weight, your body naturally tries to regain it — a process called "adaptive thermogenesis". The good news is that the NHS and private healthcare in the UK offer evidence-based strategies to help you keep the weight off, including prescription weight management medications for eligible adults. Understanding your options — whether lifestyle changes, NHS support services, or medication — is the first step to long-term success. Our free BMI calculator can help you monitor whether you're staying within your healthy weight range as you maintain your progress.
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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.
Prescription Weight Loss Medication for Weight Maintenance in the UK
Three prescription medications are licensed in the UK for weight management, and evidence shows they can help prevent weight regain after initial loss. These are prescription-only medicines that work best alongside continued dietary changes and physical activity:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist, injected once weekly. Clinical trials showed participants maintained significant weight loss when continuing treatment. Maximum dose is 15 mg weekly.
- Wegovy (semaglutide) — a GLP-1 receptor agonist, injected once weekly. The STEP trials demonstrated sustained weight maintenance in people who continued the injection. Maximum maintenance dose is 2.4 mg weekly.
- Saxenda (liraglutide) — a GLP-1 receptor agonist, injected once daily. Suitable for those preferring daily injections over weekly doses.
To be eligible, you'll typically need a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Lower BMI thresholds may apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage. A prescriber will assess whether medication is suitable for your individual circumstances. Try our free GLP-1 weight loss calculator to explore potential outcomes at different medication 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.
NHS Support and Private Access to Weight Loss Medication in the UK
NHS weight management services are available through tier 3 specialist services, typically accessed via GP referral. However, waiting lists can be substantial in many areas. Your GP can discuss whether referral is appropriate for you and explain local waiting times. If NHS access is limited in your area, private prescribing is available through online consultations with UK-licensed prescribers. A clinical assessment is required in either case — prescription weight loss medication is never issued without evaluation of your health status, medical history, and suitability.
Whether you choose NHS or private access, the aim is the same: to help you maintain your weight loss with medical support. Track your progress using our free progress tracker to monitor whether your approach is working. Talk to your GP first — they can advise whether prescription medication is appropriate for you, discuss NHS availability, or help you explore private options if NHS services are unavailable locally.
- 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.
Can prescription weight loss medication prevent weight regain after dieting?
Yes. Clinical evidence from Mounjaro (SURMOUNT trials) and Wegovy (STEP trials) shows that people who continue medication maintain significant weight loss better than those who stop. However, medication works best alongside continued healthy eating and physical activity — it's not a replacement for lifestyle changes.
How long do I need to take weight loss medication to maintain weight loss?
Duration depends on your individual circumstances and how your body responds. Some people maintain weight loss indefinitely on medication, while others may eventually reduce or stop treatment. Your prescriber will review your progress regularly and adjust the plan accordingly.
What happens to weight loss when you stop taking Mounjaro or Wegovy?
Some weight regain is common when stopping GLP-1 or GIP/GLP-1 medication. Research shows that weight regain varies — some people maintain most of their loss, others regain gradually. This is why continued healthy eating and exercise remain important whether or not you use medication long-term.
Can I get weight loss medication through the NHS in the UK?
Yes, through tier 3 specialist weight management services. Access is typically via GP referral. Availability and waiting times vary significantly by region (ICB). Ask your GP whether you're eligible and what the local pathway and waiting time are. Private prescribing is also available without NHS referral.
Is prescription weight loss medication suitable for anyone wanting to maintain weight loss?
No. Prescription weight loss medications are only suitable for adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (diabetes, high blood pressure, sleep apnoea). A prescriber must assess your individual health and medical history. Your GP or an online prescriber can advise whether you're eligible. ```
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.