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
Estrogen Replacement and Weight Loss — What You Need to Know
Hormone replacement therapy (HRT) and estrogen-based treatments can influence weight management, particularly during menopause. Whilst hormonal changes may affect metabolism and fat distribution, effective weight management strategies remain available in the UK. If you're experiencing weight changes alongside estrogen replacement, understanding your options — from lifestyle changes to prescription weight loss medication — can help you take control of your health. Your GP can provide personalised guidance based on your individual circumstances.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 for Weight Management
If you're taking estrogen replacement and struggling with weight, several prescription weight loss medications are licensed in the UK for eligible adults. These include Mounjaro (tirzepatide), a dual GIP and GLP-1 receptor agonist, and Wegovy (semaglutide), a GLP-1 medication — both available as once-weekly injections. Saxenda (liraglutide) is also available as a daily injection.
Eligibility typically requires a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions such as high blood pressure or type 2 diabetes. In clinical trials, Mounjaro helped participants lose an average of 15–21% of body weight, whilst Wegovy showed similar results around 14–15%. These medications work alongside a reduced-calorie diet and increased physical activity — they are not replacements for lifestyle changes.
Access is available through NHS specialist weight management services or private online prescribing following a clinical assessment. A prescriber will evaluate whether these medications are appropriate for you, considering any interactions with your HRT or other treatments.
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 Access and Taking the Next Step
If you're taking estrogen replacement and concerned about weight gain, start a conversation with your GP. They can assess your individual situation, discuss whether your weight changes are related to hormonal factors, and explore options including referral to NHS specialist weight management services (Tier 3). Many areas now have access to prescription weight loss medication through the NHS, though waiting times vary significantly by region.
Alternatively, you can pursue private prescription weight loss treatment through a UK-licensed prescriber without an NHS referral. Either route requires a clinical assessment to ensure the medication is safe and appropriate for you. Use our free BMI calculator above to understand where you stand, and consider tracking your progress with our progress tracker as you explore your options. Sustainable weight management during hormonal changes is achievable with the right support.
- 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 hormone replacement therapy cause weight gain?
HRT can affect weight distribution and metabolism in some people, though not everyone gains weight. Factors include the type of hormone, dose, and individual physiology. If you're concerned about weight changes whilst on HRT, discuss this with your GP — they can adjust your treatment or explore additional support.
Can I take weight loss injections whilst on estrogen replacement?
Prescription weight loss medications like Mounjaro and Wegovy can be used by people on HRT, but a prescriber must assess your individual situation and review all your medications. Always inform your prescriber about your HRT treatment before starting any new medication.
How do I access prescription weight loss medication on the NHS?
Ask your GP for a referral to your local specialist weight management service (Tier 3). They will assess your eligibility based on BMI and health conditions. Availability varies by region, and waiting times can be several months. Private options are also available without NHS referral.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections licensed for weight management in the UK. Mounjaro is a dual GIP and GLP-1 agonist (maximum 15 mg), whilst Wegovy is a GLP-1 agonist only (maximum 2.4 mg). Clinical trial data suggests similar weight loss outcomes, though individual results vary. Your prescriber will recommend the most appropriate option for you.
Will weight loss medication work alongside my estrogen replacement?
Yes, weight loss medications can work alongside HRT. However, prescription weight loss injections may affect how your body absorbs some oral medications, so your prescriber needs to review your full medication list. Never start or stop any medication without consulting your GP or prescriber.
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.