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
Drugs To Help Lose Weight — What Are Your Options?
If you're looking for drugs to help lose weight in the UK, you have several options available depending on your circumstances. Weight loss support ranges from free NHS programmes and lifestyle changes through to prescription medications and specialist services. Understanding what's available, how to access it, and which approach suits you is the first step toward sustainable weight loss. This guide covers the full spectrum of weight loss methods in the UK and how to choose the right one for your health needs.
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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 Support Options Available in the UK
Weight loss in the UK is supported through a structured NHS approach across four tiers. Tier 1 offers self-help resources, digital tools, and community weight management programmes — all free and accessible without referral. Tier 2 provides primary care-based interventions through your GP, including behaviour change programmes like the NHS Weight Loss Plan. Tier 3 is specialist multidisciplinary weight management services where prescription weight loss medication may be prescribed — this is where drugs like Mounjaro (tirzepatide) and Wegovy (semaglutide) are typically initiated. Tier 4 is bariatric surgery for severe obesity with significant health complications. Prescription weight loss drugs are not a starting point; they're prescribed when other approaches need additional support. Use our free BMI calculator above to understand where your weight sits on the NHS scale, and our GLP-1 weight loss calculator can help estimate potential results if medication is considered.
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 Access Weight Loss Drugs in the UK
Prescription weight loss medications in the UK require a clinical assessment and prescription from a licensed healthcare professional. NHS access is through tier 3 specialist weight management services — your GP can refer you, though waiting times vary significantly by region. Private access is available through GPhC-registered online pharmacies following an online consultation. Both routes require assessment of your BMI, health history, and weight-related conditions before prescription. Weight loss drugs work best alongside reduced-calorie diet and increased physical activity — they're a tool to support lifestyle changes, not a replacement for them. Track your progress using our free progress tracker to monitor results over time.
- 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 prescription weight loss drugs are available in the UK?
Three main medications are licensed for weight loss in the UK: Mounjaro (tirzepatide, once-weekly injection), Wegovy (semaglutide, once-weekly injection), and Saxenda (liraglutide, daily injection). All are GLP-1 or GIP/GLP-1 receptor agonists that work by reducing appetite and helping you feel fuller after smaller meals. Mounjaro may provide slightly greater average weight loss in clinical trials, but individual results vary significantly.
Am I eligible for weight loss drugs on the NHS?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with a weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea. South Asian, Chinese, Black African, and Black Caribbean adults may be eligible at lower BMI thresholds due to higher health risks. Your GP or a specialist can assess your individual eligibility.
What's the difference between NHS and private weight loss drug access?
NHS access is through tier 3 specialist services (longer waiting times, free on prescription) whilst private access is through online prescribing services (faster, you pay for the medication). Both require clinical assessment. NHS availability varies by region; private services are available nationwide. Most people start with tier 1 or 2 support first.
How much weight can I expect to lose with weight loss drugs?
Clinical trials show average weight loss of 15–21% of body weight over several months with prescription medications like Mounjaro, or around 15% with Wegovy. However, individual results vary considerably — some people lose more, others less. Weight loss also depends on diet, physical activity, and personal metabolism. Our GLP-1 calculator can provide personalised estimates.
Are weight loss drugs safe?
Prescription weight loss drugs are approved by the MHRA and have undergone clinical trials. Common side effects include nausea and stomach issues, which usually improve over time. Serious side effects are rare. However, they're not suitable for everyone — pregnant women, those with certain medical conditions, and people under 18 cannot take them. Always discuss risks and benefits with your GP or prescriber before starting.
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.