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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Diet Food Plan for Weight Loss — UK Medication & Support
A structured diet food plan is an essential foundation for sustainable weight loss in the UK. However, many people find that dietary changes alone are challenging. If you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions, prescription weight loss medications may be available to you alongside your food plan. This guide covers both dietary approaches and UK-licensed medication options to support your weight management uk journey.
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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.
UK-Licensed Prescription Weight Loss Options
Three prescription medications are currently licensed in the UK for weight management:
- Mounjaro (tirzepatide) — a once-weekly injection that activates dual GIP and GLP-1 pathways. Clinical trials showed average weight loss of approximately 15–21% body weight alongside a reduced-calorie diet and physical activity.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection with average weight loss of around 14.9% body weight in clinical trials.
- Saxenda (liraglutide) — a once-daily GLP-1 injection offering similar outcomes to Wegovy.
All three are prescription-only medicines that work by helping reduce appetite and food cravings. They support your diet food plan by making it easier to maintain a reduced-calorie intake. Results vary significantly between individuals, and medication works best when combined with dietary changes and increased physical activity — not as a replacement for them.
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 vs Private Access & Getting Started
In the UK, weight loss medication is available through NHS specialist weight management services (tier 3 services) or private online prescribing. NHS access typically requires a GP referral and varies by region; waiting lists can be lengthy. Private access is faster and does not require NHS referral, but involves a cost.
To find out if you are eligible, start by speaking with your GP about your weight management goals and ask for a referral to specialist weight loss services if appropriate. They can assess whether prescription medication is suitable for you based on your BMI, health history, and any weight-related conditions. Use our free BMI calculator above to check your current BMI, then discuss the results with your GP as a starting point.
Whether you choose NHS or private routes, prescription weight loss medications are always prescribed following a clinical assessment — you cannot buy them without a prescription from a licensed prescriber. A healthcare professional will review your medical history, current medications, and suitability before issuing a prescription. Remember: medication is a tool to support your diet food plan, not a standalone solution. For best results, combine any prescribed medication with a balanced, reduced-calorie diet, physical activity, and lifestyle changes.
- 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 use prescription weight loss medication without changing my diet?
No. Weight loss medications work best alongside a reduced-calorie diet and increased physical activity. They support your efforts by reducing appetite and cravings, making it easier to stick to your diet food plan — but they are not a replacement for dietary changes. Combining medication with lifestyle modifications produces the best outcomes.
What is the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections for weight management. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials showed Mounjaro may produce slightly higher average weight loss (~15–21% vs ~14.9%), but results vary individually. Your prescriber will recommend the most suitable option for you.
How long does it take to see weight loss results with prescription medication?
Results typically become noticeable within 4–6 weeks of starting treatment, though some people see changes sooner. Weight loss is usually gradual and sustainable. The pace depends on your starting weight, dose, diet adherence, and physical activity. Our free progress tracker can help you log changes over time.
Am I eligible for weight loss medication on the NHS?
NHS prescription weight loss medication is typically available for adults with a BMI of 30 or above, or 27–29.9 with weight-related conditions (type 2 diabetes, high blood pressure, sleep apnoea, cardiovascular disease). Access varies by region and requires referral to a specialist weight management service. Speak with your GP to ask about local services and eligibility.
What diet food plan should I follow while taking weight loss medication?
A balanced, reduced-calorie diet works best. Focus on whole foods, adequate protein, vegetables, and wholegrain carbohydrates. Your prescriber or a dietitian can provide a personalised plan. Use our free weight loss calculator to estimate potential outcomes at different doses, then discuss a suitable dietary plan with your healthcare team.
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.