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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Shake Drinks For Weight Loss — What Works in the UK
Weight loss shakes can be a useful part of a healthy diet plan, but for many people seeking more substantial support, prescription weight management medication offers a proven alternative. In the UK, several evidence-based prescription options are available for eligible adults, including GLP-1 medications like Mounjaro and Wegovy. These prescription treatments have shown clinical effectiveness in helping people lose weight alongside lifestyle changes. If you're considering any weight loss approach, it's worth understanding all your options — including both dietary aids and prescription medications that might be suitable for you.
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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 Prescription Weight Loss Medication Options
If you're exploring weight loss solutions, the UK healthcare system offers several prescription weight management medications for eligible adults. These are different from commercial weight loss shakes or supplements and have been clinically tested and approved by UK regulators.
Three main prescription options available:
- Mounjaro (tirzepatide) — once-weekly injection, dual GIP and GLP-1 receptor agonist. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks.
- Wegovy (semaglutide) — once-weekly injection, GLP-1 receptor agonist. Average weight loss of approximately 15% of body weight in clinical trials.
- Saxenda (liraglutide) — daily injection, GLP-1 receptor agonist. Prescribed less frequently than Mounjaro or Wegovy.
All three are prescription-only medicines requiring clinical assessment. Eligibility includes adults with a BMI of 30 or above, or 27 or above with weight-related health conditions like type 2 diabetes, high blood pressure, or cardiovascular disease.
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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 — Getting Started
In the UK, prescription weight loss medication is available through two routes: NHS specialist services or private prescribing. NHS access typically involves referral to a tier 3 specialist weight management service through your GP — though availability and waiting times vary significantly by region. Private access is faster and doesn't require an NHS referral; you'll have an online consultation with a UK-licensed prescriber who will assess your eligibility based on your BMI and health history.
To explore whether prescription medication is right for you: Start by speaking with your GP about your weight management goals and health concerns. They can assess your current BMI using our free BMI calculator, discuss whether NHS referral is appropriate, and answer questions about safety and effectiveness. If you prefer a faster route, private prescribing is available through regulated UK services following a clinical assessment.
- 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.
How do prescription weight loss medications compare to diet shakes?
Weight loss shakes can support a reduced-calorie diet, but prescription medications like Mounjaro and Wegovy work differently — they use GLP-1 hormone pathways to reduce appetite and food cravings at a physiological level. Clinical trials show prescription medications deliver substantially greater average weight loss than diet products alone. Both work best alongside lifestyle changes and a healthy diet.
Am I eligible for prescription weight loss medication on the NHS?
NHS eligibility typically requires a BMI of 30 or above, or 27 or above if you have weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Some groups (South Asian, Chinese, Black African, or Black Caribbean adults) have lower BMI thresholds due to higher health risks. Your GP can assess your eligibility and discuss referral to specialist services.
What's the difference between Mounjaro and Wegovy?
Both are once-weekly injections but work slightly differently. Mounjaro is a dual GIP and GLP-1 receptor agonist and achieved average weight loss of 15–21% in clinical trials. Wegovy is a GLP-1 receptor agonist alone with average weight loss of approximately 15%. Your prescriber will help determine which is more suitable based on your health profile and needs.
How quickly can I access prescription weight loss medication in the UK?
NHS access can involve waiting lists of several months depending on your region and tier 3 service availability. Private prescribing through UK-regulated services is faster — typically requiring an online clinical assessment and prescription within days. Both routes require assessment by a licensed prescriber to ensure the medication is appropriate for you.
Do weight loss medications work without diet and exercise changes?
No. Prescription weight loss medications are most effective alongside a reduced-calorie diet and increased physical activity. Clinical trials achieved their results by combining medication with lifestyle support. Your GP or prescriber will discuss what dietary and exercise changes are recommended alongside any prescription medication.
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.