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
Does Estrogen Replacement Help With Weight Loss?
Estrogen replacement therapy (HRT) is primarily used to manage menopausal symptoms like hot flushes and night sweats, not specifically for weight loss. However, oestrogen does play a role in metabolism and body weight regulation. Some women report modest weight changes during HRT, but evidence for direct weight loss is limited. If you're looking for evidence-based weight management in the UK, prescription options like GLP-1 medications may be worth discussing with your GP, especially if you have a BMI of 30 or above, or 27 with weight-related health conditions.
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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 Options
If you're interested in prescription weight loss medication in the UK, several licensed options are available through NHS specialist services or private prescription. Mounjaro (tirzepatide) is a once-weekly injection that works as a dual GIP and GLP-1 receptor agonist, helping regulate appetite and food intake. Wegovy (semaglutide) is another once-weekly GLP-1 injection option. Both are prescription-only and require a clinical assessment to determine eligibility.
- Mounjaro: clinical trials showed average weight loss of 15–21% body weight over 72 weeks, alongside diet and exercise
- Wegovy: evidence suggests average weight loss of around 15% body weight, with results varying between individuals
- Both are used as part of a comprehensive weight management approach, not as standalone treatments
Access through the NHS is via tier 3 specialist weight management services, though availability varies by region. Private prescription options are also available following an online clinical assessment.
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.
Eligibility and Next Steps
To find out whether prescription weight loss medication is right for you, start by discussing your health and weight goals with your GP. They can assess your BMI, any weight-related health conditions (such as type 2 diabetes, high blood pressure, or sleep apnoea), and refer you to specialist services if appropriate.
You can also use our free BMI calculator to check where your weight falls, and try our GLP-1 weight loss calculator to see projected outcomes at different medication doses. These tools can help you prepare for a conversation with your healthcare team about whether prescription weight management is suitable for you.
- 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.
Does HRT cause weight loss?
HRT is not designed for weight loss. While oestrogen affects metabolism, evidence shows HRT typically results in modest weight changes — sometimes weight gain, sometimes stability. Weight management and HRT serve different health purposes. If weight loss is your goal, discuss prescription weight loss options with your GP.
What prescription weight loss medications are available in the UK?
The main UK-licensed options are Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All are prescription-only and require clinical assessment. Mounjaro and Wegovy are once-weekly injections. Eligibility depends on BMI and health factors — your GP can advise.
How much weight can I lose with prescription medication?
Clinical trial data shows average weight loss of 15–21% body weight with Mounjaro and around 15% with Wegovy, but individual results vary significantly. These medications work alongside reduced-calorie diet and exercise. Results depend on your starting weight, adherence, and lifestyle factors.
Can I get weight loss injections on the NHS?
Yes, prescription weight loss medications are available through NHS tier 3 specialist weight management services. However, access varies significantly by region and waiting times can be lengthy. Your GP can refer you. Private prescription options are also available without NHS referral.
What does it mean if I'm eligible for weight loss medication?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like diabetes, high blood pressure, or sleep apnoea. Eligibility is assessed individually by a healthcare professional. Lower thresholds apply for people of South Asian, Chinese, Black African, or Black Caribbean heritage.
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.