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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Fast Weight Loss Meal Plan: UK Prescription Medication Options
A fast weight loss meal plan works best when combined with professional support. In the UK, prescription weight management medications like Mounjaro and Wegovy are now available for eligible adults alongside diet changes. These GLP-1 and dual-action medications can help reduce appetite and support sustainable weight loss when used with a reduced-calorie diet and increased physical activity. Our GLP-1 weight loss calculator can help you explore potential outcomes, whilst understanding your BMI and calorie needs is essential for any effective plan. This guide covers what prescription options are available in the UK, who qualifies, and how to access them through your GP or private prescribing.
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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 Management Options
Three prescription medications are currently licensed for weight management in the UK: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Mounjaro is a once-weekly injection that works by activating dual GIP and GLP-1 hormone pathways, helping regulate appetite and food intake. In clinical trials, Mounjaro users lost an average of 15–21% of body weight over 72 weeks when combined with diet and exercise. Wegovy is also once-weekly and works via GLP-1 activation alone, with clinical trial results showing average weight loss of around 15% of body weight. Eligibility requires a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds apply due to higher health risks at lower weight levels. All three medications are prescription-only and require clinical assessment before dispensing.
- Mounjaro: 2.5–15 mg once weekly
- Wegovy: 0.25–2.4 mg once weekly
- Saxenda: 0.6–3 mg once daily
Each works alongside a reduced-calorie meal plan, not instead of one. Individual results vary significantly based on lifestyle, adherence, and personal metabolism.
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 and Next Steps
NHS access: Prescription weight loss medication is available through NHS specialist tier 3 and tier 4 weight management services. Your GP can refer you if you meet eligibility criteria, but waiting lists vary significantly by region (ICB). Some areas have several-month to multi-year waits. Private access: Available through online clinical assessment with UK-licensed prescribers, typically faster and without waiting lists. To find out if prescription medication is right for you, book an appointment with your GP and discuss your weight health, BMI, and any weight-related conditions. Your GP can assess eligibility and refer you to specialist services if appropriate. Alternatively, you can access a private clinical assessment online if you prefer quicker access. Use our BMI calculator to check your personal BMI before your conversation with your GP—this helps guide the discussion about treatment options and whether medication may be suitable for your circumstances.
- 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.
Are fast weight loss meal plans with medication safe?
When prescribed and monitored by a qualified healthcare professional, weight loss medications are safe for eligible adults. Prescription medications require clinical assessment to ensure suitability. A safe weight loss rate is 0.5–1 kg per week. Medications are most effective when combined with a reduced-calorie diet, increased physical activity, and behavioural changes. Always follow your prescriber's guidance and report any side effects.
Can I get Mounjaro or Wegovy through the NHS?
Yes, both Mounjaro and Wegovy are available through NHS specialist weight management services for eligible adults. Access requires a GP referral to tier 3 services. Availability and waiting times vary significantly by region. Private options are also available through online prescribing services if you prefer faster access. Check with your local ICB for NHS availability in your area.
What makes a fast weight loss meal plan work with medication?
Prescription weight loss medications like Mounjaro and Wegovy work best with a structured reduced-calorie meal plan, typically 500–750 kcal below your maintenance level. The medication reduces hunger and cravings, making it easier to stick to the plan. Combined with increased physical activity and behavioural support, results are more sustainable. Try our GLP-1 weight loss calculator to see projected outcomes at different doses.
How do I know if I'm eligible for prescription weight loss medication?
Eligibility requires a BMI of 30 or above, or 27 or above with weight-related health conditions (diabetes, hypertension, cardiovascular disease, sleep apnoea). For South Asian, Chinese, Black African, or Black Caribbean adults, lower thresholds apply. Use our BMI calculator to check your BMI, then book a GP appointment to discuss eligibility. Your GP or a licensed prescriber will conduct a full clinical assessment.
How quickly will I lose weight with Mounjaro or Wegovy?
Clinical trials show average weight loss of 15–21% of body weight over 6–12 months, but individual results vary significantly. Most people see gradual progress over 4–8 weeks as their dose increases. Weight loss is fastest in the first 3–4 months, then typically stabilises. Medication works best alongside consistent diet and exercise changes. Results depend on adherence, metabolism, and lifestyle factors.
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.