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
Can Estrogen Replacement Help with Weight Loss?
Estrogen replacement therapy (HRT) does not directly cause weight loss, but hormonal changes during menopause can make weight management more challenging. Many women find that addressing hormonal imbalance helps them regain control of their weight. If you're looking to lose weight while taking HRT, prescription weight loss medication alongside lifestyle changes may help. Our free BMI calculator and weight loss calculator can help you understand your current health position and explore what weight management options might suit you.
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.
Hormones and Weight Management During Menopause
Oestrogen plays a significant role in weight regulation. When oestrogen levels drop during perimenopause and menopause, many women experience increased appetite, slower metabolism, and a tendency to store fat around the midsection rather than hips and thighs. This is not inevitable weight gain — it's a shift in how your body manages weight.
- HRT can help stabilise appetite signals and may make weight management feel more achievable for some women
- Weight loss remains possible during HRT through calorie deficit and increased physical activity
- Individual responses vary — some women lose weight easily on HRT, others find it requires more effort
- Timing matters — starting HRT earlier in perimenopause may support easier weight management than waiting until later
However, HRT is not a weight loss treatment. If you need additional support, prescription weight loss medication combined with diet and exercise may be an option to discuss with your GP.
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.
Weight Loss Medication Options for Women on HRT
GLP-1 weight loss injections like Wegovy (semaglutide) and Mounjaro (tirzepatide) are prescription-only medications licensed in the UK for weight management. In clinical trials, these medications helped adults lose an average of 14–21% of their body weight alongside reduced-calorie diet and increased physical activity. Women taking HRT can use weight loss medication — there are no absolute contraindications — but your prescriber needs to know about all medications you're taking.
Access is through NHS specialist weight management services or private online prescribing following clinical assessment. Use our GLP-1 weight loss calculator to explore potential outcomes at different doses, and discuss with your GP whether prescription weight loss support might help alongside your HRT.
- 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 gain?
HRT does not directly cause weight gain, but menopausal hormone changes can increase appetite and slow metabolism, making weight gain more likely without dietary and activity adjustments. Starting HRT may stabilise these changes and make weight management feel easier for many women.
Can I take weight loss injections while on HRT?
Yes, women on HRT can use prescription weight loss medications like Wegovy or Mounjaro. Always inform your prescriber about your HRT to ensure there are no interactions. Your GP or prescriber will assess whether weight loss medication is appropriate for you.
How much weight can I lose with Wegovy or Mounjaro?
Clinical trials showed Wegovy users lost an average of approximately 15% of body weight, and Mounjaro users lost 15–21%, over 17–20 weeks. Individual results vary significantly. Results were achieved alongside a reduced-calorie diet and increased physical activity.
What is the difference between Wegovy and Mounjaro?
Wegovy (semaglutide) is a GLP-1 receptor agonist. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, which may produce slightly greater weight loss on average. Both require a prescription and clinical assessment. Wegovy has a maximum dose of 2.4 mg weekly; Mounjaro reaches 15 mg weekly.
How do I access weight loss medication on the NHS?
Refer to your GP, who can refer you to a tier 3 specialist weight management service. NHS eligibility requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Regional availability varies — some areas have long waiting lists. Private online prescribing is also available following clinical assessment.
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.