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
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What Can I Take To Lose Weight — Evidence-Based Options
If you're looking for weight loss solutions in the UK, there are several evidence-based options available to you — from lifestyle changes to prescription medications. The most effective approach combines dietary changes, increased physical activity, and sometimes medical support. This guide covers the realistic options available on the NHS and privately, what works best for sustainable weight loss, and how to assess whether prescription weight loss treatment might be right for you. Remember that individual results vary significantly, and your GP can advise on the safest approach for your personal health situation.
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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.
What Can You Take To Lose Weight in the UK?
Weight loss in the UK typically involves a combination of approaches rather than a single "solution". Lifestyle changes remain the foundation of sustainable weight management and include a reduced-calorie diet (typically a deficit of 500 calories per day for approximately 0.5 kg per week loss), increased physical activity, and behaviour change support.
For weight loss that focuses on NHS weight management, there are several options available:
- NHS Weight Loss Plan: Free digital support for tier 1 self-management
- Tier 3 specialist services: Multidisciplinary weight management programmes available through NHS referral
- Prescription weight loss medications: Prescription-only injections licensed for weight loss in the UK, typically prescribed through specialist services
- VLCD programmes: Very low calorie diets (under 800 kcal/day) available through specialist NHS services under medical supervision
For safe and sustainable weight loss UK, the NHS recommends losing no more than 0.5 to 1 kg per week. Use our free BMI calculator above to assess your current weight category and understand whether weight loss might benefit your health.
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.
Prescription Weight Loss Medications Available in the UK
Prescription weight loss injections are available in the UK for eligible adults and are sometimes referred to as "slimming injections" or "weight loss jabs". These are GLP-1 or GIP/GLP-1 receptor agonist medications that may help reduce appetite and support weight management when used alongside dietary changes and increased physical activity.
Currently licensed in the UK are Wegovy (semaglutide), Mounjaro (tirzepatide), and Saxenda (liraglutide). In clinical trials, these medications helped participants lose an average of 14–21% of their body weight, though individual outcomes vary considerably. All are prescription-only medicines requiring clinical assessment before dispensing. Access is available through NHS specialist tier 3 weight management services or privately through GPhC-registered online prescribers. Try our free GLP-1 weight loss calculator to explore potential outcomes at different doses.
- 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 the safest way to lose weight?
The NHS recommends losing 0.5–1 kg per week through a combination of reduced-calorie diet (typically 500 kcal deficit daily), increased physical activity, and behaviour change support. This rate is sustainable and minimises muscle loss. Speak to your GP before starting any weight loss programme, especially if you have existing health conditions.
Can I get weight loss medication on the NHS?
Yes. Prescription weight loss medications are available through NHS specialist tier 3 weight management services if you meet eligibility criteria (typically BMI 30+ or 27+ with weight-related health conditions). Access varies by region and waiting times can be long. Your GP can refer you to your local service. Private access is also available through online prescribers.
What's the difference between Wegovy and Ozempic?
Both contain semaglutide, but Wegovy is licensed specifically for weight management (doses up to 2.4 mg), whilst Ozempic is approved for type 2 diabetes (doses up to 2 mg). Using Ozempic for weight loss in the UK is off-label. Wegovy is the licensed weight loss version. Only use medications as prescribed by your healthcare provider.
How much weight can I expect to lose with prescription medication?
Clinical trials show prescription weight loss injections may help achieve average weight losses of 14–21% of body weight over 68 weeks, though individual results vary significantly. Results depend on the dose, your adherence, dietary changes, and physical activity. Our GLP-1 weight loss calculator can help you estimate potential outcomes based on different doses.
Are there side effects to weight loss medications?
Yes. Common side effects include nausea, diarrhoea, vomiting, constipation, and stomach pain — usually mild and temporary. Serious but rare side effects include pancreatitis symptoms (severe stomach pain) and gallbladder issues. Always discuss potential side effects with your prescriber and report any concerning symptoms to your GP promptly.
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.