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
Healthy Eating for Weight Loss in the UK
Healthy eating is the foundation of sustainable weight loss, but for many UK adults, combining good nutrition with prescription weight management medication can be more effective. This guide covers evidence-based dietary approaches and explains how prescription options like Mounjaro and Wegovy work alongside healthy eating habits. If you're carrying excess weight and struggling with diet alone, understanding your options—including NHS and private weight loss medication—can help you find the right approach for your 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.
Nutrition and Weight Loss: What the Evidence Shows
Sustainable weight loss through healthy eating typically involves creating a calorie deficit of around 500 kcal per day, which research suggests leads to approximately 0.5 kg per week of loss. The NHS recommends focusing on whole foods, reducing ultra-processed items, and increasing fibre and protein intake—all of which support satiety and help you feel fuller for longer.
- Mediterranean diet: Strong evidence for both weight loss and cardiovascular health
- Lower calorie intake: Aim for consistent, modest deficits rather than extreme restriction
- Protein and fibre: Both increase fullness and support muscle retention during weight loss
- Hydration: Drinking water before meals can help reduce overall intake
Even a 5–10% reduction in body weight—achieved through healthy eating—can improve blood pressure, blood sugar control, and cholesterol levels. However, healthy eating works best when combined with increased physical activity and, for eligible adults, may be supported by prescription weight management medication.
Clinically BackedWeight Loss
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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 Options Available in the UK
For UK adults struggling with weight despite healthy eating efforts, three prescription weight loss medications are licensed: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are GLP-1 receptor agonist injections that work alongside diet and exercise—not instead of them. You may be eligible if your BMI is 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure.
Clinical trials show these medications can support an average loss of 15–21% of body weight when combined with healthy eating and physical activity. Access is available through NHS specialist weight management services (though waiting times vary by region) or through private online prescribing following a clinical assessment. Your GP can discuss whether prescription medication is appropriate for your situation.
- 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.
Can I lose weight with healthy eating alone?
Yes, many people lose weight successfully through diet and exercise. The NHS recommends aiming for 0.5–1 kg per week through a calorie deficit and increased activity. However, if you've tried this without success or have obesity-related health conditions, prescription medication may help. Use our free BMI calculator to check your current status and discuss options with your GP.
What's the difference between healthy eating and weight loss medication?
Healthy eating creates the foundation—it changes your habits long-term. Prescription medications like Mounjaro and Wegovy are tools that help reduce appetite and cravings alongside dietary changes. They're not replacements for healthy eating; they're prescribed alongside it. Both approaches together are more effective than either alone.
How do I know if I'm eligible for weight loss medication in the UK?
You may be eligible if your BMI is 30 or above, or 27–29.9 with weight-related conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Check your BMI using our free BMI calculator, then speak to your GP about whether prescription medication is appropriate for you.
Is weight loss medication available on the NHS?
Yes, Mounjaro and Wegovy are approved for NHS use through specialist tier 3 weight management services. However, availability varies significantly by region, and waiting lists can be lengthy. Private prescribing is also available. Your GP can explain both NHS and private options in your area.
How much weight can prescription medication help me lose?
Clinical trials show Mounjaro may help achieve average weight loss of 15–21% of body weight, and Wegovy around 15%, over 68–72 weeks—alongside healthy eating and increased physical activity. Individual results vary significantly. Our free GLP-1 weight loss calculator can show you potential outcomes at different doses. ```
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.