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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Body Cleanse for Weight Loss: UK Prescription Weight Management Options
"Body cleanse" products promise gradual weight management, but evidence-based prescription medication offers a more reliable approach for eligible UK adults. If you're exploring weight management options, NHS-approved prescription treatments like Mounjaro and Wegovy may help you lose weight sustainably alongside diet and lifestyle changes. This guide explains UK prescription weight loss medication, who qualifies, and how to access it through the NHS or private clinicians. Calculate your BMI using our free calculator to check where you currently stand, and explore whether medication-supported weight management could be right for you.
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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 Prescription Weight Loss Medications Explained
Three prescription-only medications are licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All work by activating natural appetite-control hormones.
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist injected once weekly. In clinical trials (SURMOUNT-1), participants lost an average of 15–21% of body weight over 72 weeks alongside a reduced-calorie diet and increased physical activity.
Wegovy (semaglutide) is a GLP-1 receptor agonist, also injected once weekly. STEP-1 trial data showed average weight loss of approximately 15% of body weight at 68 weeks.
Saxenda (liraglutide) is a once-daily GLP-1 injection. All three are prescription-only and require clinical assessment. Individual results vary significantly. Use our GLP-1 weight loss calculator to estimate potential weight loss 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.
UK Eligibility and How to Access Weight Loss Medication
In the UK, prescription weight loss medication may be available if you have a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, 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 lower weights.
NHS access: Request a referral from your GP to a tier 3 specialist weight management service. Waiting lists vary by region. Private access: Online clinicians can assess and prescribe if eligible. Use our free BMI calculator to check your starting point, then discuss options with your GP or a licensed prescriber.
- 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.
Is body cleanse the same as prescription weight loss medication?
No. "Body cleanse" products typically lack strong evidence and are unregulated. Prescription medications like Mounjaro and Wegovy are licensed, clinically tested, and approved by the MHRA. They work by reducing appetite and require a prescription and clinical assessment.
How much weight can I lose with Mounjaro or Wegovy?
Clinical trials show average weight loss of 15–21% of body weight over several months, but individual results vary widely. Some people lose more, some less. Results are achieved alongside diet changes and increased physical activity. Your progress depends on your starting weight, adherence, and individual physiology.
Do I need to be referred to the NHS to get prescription weight loss medication?
For NHS access, you typically need a GP referral to a specialist tier 3 weight management service. However, private clinicians can also assess and prescribe if you meet eligibility criteria. Access and waiting times vary significantly by region.
What happens if I stop taking Mounjaro or Wegovy?
Weight loss benefits are typically sustained only while taking the medication alongside healthy eating and physical activity. If treatment stops, weight may gradually return. These medications work best as part of long-term weight management, not as a structured approach.
Are there side effects I should know about?
Common side effects include nausea, diarrhoea, constipation, and stomach pain—usually mild and temporary. Serious side effects are rare but can include pancreatitis or gallbladder problems. Your prescriber will assess risks and discuss them with you before starting treatment.
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.