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
Female Extreme Weight Loss: What the Evidence Shows
Extreme weight loss in women is often achieved through a combination of prescription weight loss medications, significant dietary changes, and increased physical activity. If you've seen before and after transformations online, it's important to understand what's realistically achievable, how prescription medications work in the UK, and what medical support is available. This guide explains the evidence behind female weight loss, eligibility for NHS and private treatment, and how to set sustainable goals using our free BMI calculator and weight loss tools.
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.
How Prescription Weight Loss Medications Work for Women
GLP-1 receptor agonist medications like Wegovy (semaglutide) are prescribed to women in the UK for weight management when BMI is 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes or high blood pressure. In clinical trials, women taking the maximum dose (2.4 mg semaglutide once weekly) lost an average of around 15% of their body weight over 68 weeks — alongside a reduced-calorie diet and increased physical activity.
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist that may produce slightly higher average weight loss (15–21% in trials) because it activates two hormone pathways rather than one.
- Both medications are prescription-only and require a clinical assessment
- Both are once-weekly injections — available through NHS specialist services or private prescribers
- Individual results vary significantly — some women lose more, some less
- Medication works by reducing appetite, increasing fullness, and slowing stomach emptying
Important: These medications are not insulin and are not "clinically supported" — they work best alongside sustained dietary changes and movement.
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.
Setting Realistic Goals and Understanding Timeframes
Extreme weight loss takes time. The NHS recommends losing 0.5–1 kg per week for sustainable results — that's approximately 26–52 kg per year. A woman losing 15% of her body weight at 100 kg would lose around 15 kg (2 stone 5 lbs) over a year, not weeks. Before and after images online often show transformations over 12–24 months, not days or weeks.
Use our free GLP-1 weight loss calculator to estimate realistic outcomes at different medication doses. Check your starting BMI with our BMI calculator to understand your current health position. Track progress using our free progress tracker — sustainable weight loss is a marathon, not a sprint. If you've experienced gradual weight management previously, discuss this with your GP, as it may indicate an underlying health condition.
- 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.
What's a realistic amount of weight loss for women on Wegovy or Mounjaro?
Clinical trials show average weight loss of 15–21% body weight over 12–16 months with medication, alongside lifestyle changes. A 100 kg woman might lose 15–21 kg (2 stone 5 lbs to 3 stone 4 lbs). Individual results vary significantly — some lose more, some less. Always discuss personal expectations with your GP or prescriber.
Can I get prescription weight loss medication on the NHS?
Possibly. You must be referred to a tier 3 specialist weight management service by your GP. NHS access varies significantly by region (ICB). Waiting lists can be lengthy in many areas. Private prescribers offer faster access following an online clinical assessment, though there is a cost.
What's the difference between Ozempic and Wegovy for weight loss?
Both contain semaglutide, but Ozempic (up to 2 mg) is licensed only for type 2 diabetes — using it for weight loss is off-label. Wegovy (up to 2.4 mg) is specifically licensed in the UK for weight management. Always use the licensed medication for your indication.
Are extreme weight loss transformations on social media realistic?
Before and after images typically show 12–24 months of sustained effort, not weeks. They often involve professional photography, lighting, and sometimes image editing. Extreme transformations may also involve bariatric surgery alongside medication. Focus on your personal health metrics — BMI, energy levels, health conditions — rather than appearance alone.
Will I regain weight if I stop the medication?
Weight regain is possible if diet and activity levels return to pre-treatment patterns. Research suggests maintaining weight loss after stopping medication requires sustained lifestyle changes. Discuss long-term management plans with your GP or prescriber — some women benefit from staying on medication longer-term.
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.