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
Detox and Weight Loss Drinks — What Works in the UK?
Detox and weight loss drinks are popular, but the evidence for them is limited. While staying hydrated is important, no drink alone causes significant weight loss. In the UK, adults looking for evidence-based weight management support have access to prescription medications, NHS programmes, and clinical guidance. This guide explains what actually works, and how to explore your options if you're serious about losing weight sustainably.
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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 Options Available in the UK
If you're interested in weight management in the UK, prescription medications are available for eligible adults. These are licensed medical treatments, not supplements or drinks:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist injection, once weekly. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks, alongside diet and exercise.
- Wegovy (semaglutide) — a GLP-1 receptor agonist injection, once weekly. Average weight loss of approximately 15% body weight in clinical trials.
- Saxenda (liraglutide) — a GLP-1 receptor agonist, once daily injection. Earlier medication in this class.
These medications work by regulating appetite hormones and helping you feel fuller after smaller meals. Individual results vary significantly. All are prescription-only and require clinical assessment by a licensed prescriber to determine eligibility.
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.
Who Is Eligible, and How to Access Weight Loss Support
To access prescription weight loss medication in the UK, you typically need a BMI of 30 or above, or BMI of 27–29.9 with a weight-related health condition such as type 2 diabetes, high blood pressure, or cardiovascular disease. Use our free BMI calculator above to check your starting point instantly.
NHS route: Ask your GP about referral to a tier 3 specialist weight management service. Access varies by region and waiting times can be lengthy.
Private route: Online consultation with a UK-licensed prescriber, prescription issued if clinically appropriate, dispensed by a registered pharmacy. No NHS referral needed. Try our GLP-1 weight loss calculator to estimate potential results with different medications, then discuss eligibility with a prescriber.
Sustainable weight loss involves a combination of approaches: dietary changes, increased physical activity, and sometimes prescription support. Prescription weight loss medication works alongside lifestyle changes, not instead of them. Your GP can provide personalised advice about whether medication is appropriate for your individual health situation and goals.
- 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.
Do detox drinks actually help you lose weight?
Detox drinks have limited scientific evidence for weight loss. Staying hydrated is important, but no drink alone causes significant fat loss. Weight loss requires a calorie deficit, which means eating less energy than you burn. For proven support, talk to your GP about prescription options or evidence-based lifestyle changes.
What's the difference between detox drinks and prescription weight loss medication?
Detox drinks are unregulated products with minimal evidence. Prescription weight loss medications like Mounjaro and Wegovy are licensed medicines tested in clinical trials involving thousands of people. They work on hormone pathways that regulate appetite. They require a prescription and clinical assessment, whereas drinks don't.
Can I get prescription weight loss medication on the NHS in the UK?
Yes. NHS specialist weight management services (tier 3) can prescribe medications like tirzepatide and semaglutide for eligible adults. Eligibility typically requires BMI 30+ or BMI 27–29.9 with a weight-related health condition. Ask your GP for a referral. Private prescribing is also available without NHS referral.
How much weight can I expect to lose with prescription medication?
Clinical trials show average weight loss of 15–21% of body weight over 72 weeks with Mounjaro, and approximately 15% with Wegovy. Individual results vary significantly based on diet, exercise, genetics, and other factors. No outcome is assured. A prescriber can discuss realistic expectations for your situation.
How do I find out if I'm eligible for weight loss medication?
Calculate your BMI using our free BMI calculator above. If your BMI is 30 or above, or 27–29.9 with a weight-related health condition, you may be eligible. The next step is to speak with your GP (for NHS referral) or complete an online consultation with a UK-licensed prescriber (for private access).
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.