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
How to Increase Metabolism for Weight Loss with Prescription Medication
While metabolism is influenced by genetics, age, and activity level, prescription weight management medications offer evidence-based support for adults struggling with weight loss in the UK. Medications like Mounjaro and Wegovy work by affecting how your body regulates appetite and processes food, effectively supporting your metabolic health. These are available through both NHS specialist services and private prescribing following clinical assessment. Our GLP-1 weight loss calculator can help you explore potential outcomes with these medications.
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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 Medications
Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only medicines licensed in the UK for weight management. Both are GLP-1 receptor agonists that work by supporting appetite regulation and helping your body process food more efficiently. In clinical trials, Mounjaro showed average weight loss of 15–21% of body weight, whilst Wegovy showed approximately 15% — though individual results vary significantly.
- Mounjaro: Dual GIP and GLP-1 agonist, once-weekly injection, doses from 2.5mg to 15mg
- Wegovy: GLP-1 agonist, once-weekly injection, doses from 0.25mg to 2.4mg
- Saxenda: GLP-1 agonist, daily injection, doses up to 3mg
Eligibility typically 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 adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply. All three medications are used alongside reduced-calorie diet and increased physical activity for best results.
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.
Accessing Weight Loss Medication in the UK
In the NHS, prescription weight loss medication is available through specialist tier 3 weight management services — not standard GP prescription. You'll typically need a referral from your GP, though availability varies significantly by region and waiting lists can be lengthy. Private access is available through UK-licensed online prescribers following an online clinical assessment; this route often has shorter timelines but involves cost.
Your first step is a conversation with your GP about whether prescription weight loss treatment is appropriate for you. They can assess your eligibility, discuss your health goals, and explain whether NHS referral or private prescribing is the right option. Use our free BMI calculator above to check your current BMI and understand whether you might meet eligibility criteria before your appointment.
- 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 metabolism be increased naturally for weight loss?
Yes, some factors support metabolic activity — regular strength training builds muscle (which increases resting metabolism), staying active, eating adequate protein, and staying hydrated all help. However, for many adults, particularly those with BMI over 30, these changes alone may not be sufficient. That's where prescription weight management options can provide additional support.
How do Mounjaro and Wegovy increase metabolism?
These medications don't directly "speed up" metabolism in the traditional sense. Instead, they're GLP-1 receptor agonists that help regulate appetite hormones, reduce cravings, slow gastric emptying, and support your body's ability to process food efficiently. This creates a more sustainable calorie deficit without constant hunger, which supports weight loss.
Who is eligible for prescription weight loss medication in the UK?
Generally, adults with a BMI of 30 or above, or 27 or above with weight-related health conditions (diabetes, hypertension, cardiovascular disease), may be eligible. South Asian and Black heritage adults may qualify at lower BMI thresholds. Your GP or a licensed prescriber can assess your individual eligibility after a clinical assessment.
What's the difference between NHS and private weight loss medication access?
NHS access is through specialist weight management services (tier 3) following GP referral — free but with potential waiting lists. Private access is through UK-licensed online prescribers following an online assessment — faster but involves cost. Both routes require clinical assessment and prescription from a licensed prescriber.
How much weight can I lose with prescription weight loss medication?
Clinical trials show average weight loss of 15–21% of body weight with these medications, though individual results vary considerably. Weight loss also depends on adherence to reduced-calorie diet and increased physical activity. Our GLP-1 weight loss calculator can help you explore potential outcomes based on your starting weight and dose.
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.