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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Simple Weight Loss Plan Reviews in the UK
If you're looking for a straightforward weight loss plan in the UK, prescription weight management medication may be part of your journey. This guide reviews the main evidence-based options available to eligible adults—from NHS support to licensed weight loss injections. We'll help you understand how these approaches work, who can access them, and how to start a conversation with your GP about what might suit your circumstances. Weight management is personal, and knowing your options is the first step.
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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.
UK-Licensed Weight Loss Medication Options
Three prescription-only medications are licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All three are GLP-1 receptor agonist or dual GIP/GLP-1 agonist medications that work by supporting appetite control and helping you feel fuller for longer.
- Mounjaro—a once-weekly injection with dual GIP and GLP-1 action. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity.
- Wegovy—a once-weekly GLP-1 injection. Average weight loss in trials was around 15% of body weight at the maximum dose.
- Saxenda—a daily GLP-1 injection offering similar results to Wegovy but requiring daily administration instead of weekly.
All three require a prescription following clinical assessment. Individual results vary significantly based on adherence, diet, and exercise. These are tools to support prescription weight loss, not replacements for lifestyle changes.
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 and Eligibility
NHS access is available through tier 3 specialist weight management services, though availability and waiting lists vary significantly across regions. Your GP can refer you if you meet criteria: typically 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.
Private access is available without NHS referral through GPhC-registered online prescribers following an online clinical assessment. This route is faster but involves private costs.
To find out if prescription weight loss is right for you, start with your GP—they can discuss your BMI weight loss targets, assess your health, and either refer you to NHS services or discuss private options. Use our free BMI calculator and GLP-1 weight loss calculator to understand your starting point and potential outcomes 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 counts as a simple weight loss plan in the UK?
A simple weight loss plan focuses on clear, sustainable steps—reduced-calorie diet, increased physical activity, and where eligible, prescription support like GLP-1 medication. The NHS weight loss plan, Mounjaro, and Wegovy are all evidence-based approaches. Your GP can help tailor a plan to your health and circumstances.
Am I eligible for prescription weight loss medication on the NHS?
NHS eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions (diabetes, high blood pressure, sleep apnoea). Lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults. Your GP can assess your eligibility and refer you to specialist services.
How much weight can I expect to lose with these medications?
Clinical trials show average weight loss of 15–21% of body weight with Mounjaro and around 15% with Wegovy, alongside diet and exercise. Individual results vary significantly. These medications support weight loss but are not assured to produce specific outcomes for any person.
What's the difference between Mounjaro and Wegovy?
Mounjaro uses dual GIP and GLP-1 action and showed slightly higher average weight loss in trials (up to 21% vs 15% for Wegovy). Wegovy is a GLP-1 agonist only. Both are once-weekly injections. Your prescriber will assess which is more suitable for you.
How do I start exploring weight loss medication options?
Book an appointment with your GP to discuss your weight management goals and health. Ask about NHS referral to specialist services or discuss private options. Our free tools—BMI calculator, weight converter, and GLP-1 weight loss calculator—can help you prepare for that conversation with data about your current health metrics.
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.