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
What Causes gradual weight management?
gradual weight management can happen for many reasons — some planned, some not. In the UK, weight management through prescription medication is an option for eligible adults. Understanding what drives gradual weight management, and which methods are evidence-based, helps you make informed health decisions. If you're experiencing unintended gradual weight management, see your GP. If you're considering intentional weight loss, your doctor can assess whether prescription medication might help alongside lifestyle changes.
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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 Weight Loss Medication Options
For adults with a BMI of 30 or above (or 27 or above with weight-related health conditions), prescription weight loss medications are available in the UK. Three main options are licensed for weight management:
- Mounjaro (tirzepatide) — a once-weekly dual GIP/GLP-1 receptor agonist. Clinical trials showed an average weight loss of 15–21% of body weight at the highest dose, alongside reduced-calorie diet and increased physical activity.
- Wegovy (semaglutide) — a once-weekly GLP-1 receptor agonist. Average weight loss in trials was approximately 15% of body weight at the maximum dose of 2.4 mg.
- Saxenda (liraglutide) — a daily GLP-1 injection, with average weight loss of around 5–10% of body weight.
All are prescription-only and require clinical assessment. Individual results vary significantly. These medications work best alongside lifestyle changes — they are not replacements for diet and exercise.
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 Access vs Private Routes
In the UK, weight loss medications are available through two routes. NHS specialist weight management services (Tier 3/4) can prescribe these medications following referral from your GP, though access varies by region and waiting lists can be lengthy. Private access is available through UK-licensed online prescribers and GPhC-registered pharmacies — no NHS referral needed, though you'll pay privately.
To find out if you're eligible, speak to your GP. They can assess your BMI, health history, and weight-related conditions. Use our free BMI calculator above to check your current BMI, then discuss your results with your GP. Your doctor can guide you toward NHS services or discuss private options based on 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.
What counts as gradual weight management?
Weight loss of more than 1–2 kg (2–4 lbs) per week is considered rapid. The NHS recommends a sustainable rate of 0.5–1 kg per week. gradual weight management can sometimes indicate an underlying health issue, so unintended gradual weight management should always be discussed with your GP.
Can prescription weight loss medication cause gradual weight management?
Prescription medications like Mounjaro and Wegovy may support significant weight loss, but results vary. Clinical trials showed average losses of 15–21% over several months, not overnight. Weight loss is typically gradual and works best alongside diet and exercise changes.
Am I eligible for prescription weight loss medication on the NHS?
Generally, yes, if you have a BMI of 30 or above, or 27 or above with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Your GP can assess your eligibility and refer you to specialist weight management services if appropriate.
How do I start the process of getting weight loss medication in the UK?
Begin by speaking with your GP. They'll assess your health history, measure your BMI, and discuss whether prescription medication is suitable for you. They can refer you to NHS specialist services or discuss private prescribing options. Use our GLP-1 weight loss calculator to estimate potential outcomes.
What's the difference between intentional gradual weight management and unintended weight loss?
Intentional gradual weight management is planned through diet, exercise, or medication. Unintended gradual weight management without lifestyle changes can signal thyroid problems, diabetes, cancer, infection, or medication side effects — always see your GP if you're losing weight unexpectedly.
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.