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
Can Acid Reflux Cause Weight Loss?
Yes, acid reflux (gastro-oesophageal reflux disease or GORD) can sometimes lead to weight loss, though it's not a reliable or safe way to lose weight. Reflux discomfort may reduce appetite or make eating painful, resulting in reduced food intake. However, weight loss related to reflux is often unintentional and can indicate an underlying health issue that needs GP attention. If you're experiencing both reflux and weight loss, it's important to speak with your healthcare provider. For intentional weight management in the UK, prescription weight loss medication is available for eligible adults—we'll explain your options below.
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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
If you're looking to manage your weight intentionally, several prescription weight loss medications are licensed in the UK and available through NHS specialist services or private online prescribing. These medications work very differently from reflux-related weight loss and are clinically proven to support sustainable weight management.
Mounjaro (tirzepatide) is a once-weekly injection approved for adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions. In clinical trials, it helped participants lose an average of 15–21% of their body weight alongside a reduced-calorie diet and increased physical activity. Wegovy (semaglutide) is another once-weekly GLP-1 injection, with clinical evidence showing average weight loss of around 15% of body weight. Both medications are prescription-only and require a clinical assessment to determine eligibility.
A third option, Saxenda (liraglutide), is a daily injection also licensed for weight management in the UK. All three require prescriptions and work best alongside lifestyle changes—they are not standalone solutions.
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
In the UK, prescription weight loss medication is accessible through two routes: NHS specialist weight management services (tier 3 services, typically requiring a GP referral) or private online prescribing (through GPhC-registered pharmacies following a clinical assessment). NHS access varies significantly by region and waiting times can be lengthy. Private prescribing is faster but involves a cost. Whichever route you choose, you'll need to discuss your personal health history, current medications, and weight loss goals with a prescriber.
If you're experiencing unintended weight loss alongside acid reflux, speak to your GP first—this may need investigation before starting any weight loss medication. If you're interested in prescription weight management options and think you may be eligible, use our free GLP-1 weight loss calculator above to understand potential outcomes, and speak with your GP or a licensed prescriber about suitability for your individual 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.
Can acid reflux alone cause significant weight loss?
Acid reflux can reduce appetite and make eating uncomfortable, leading to lower food intake and gradual weight loss. However, significant or gradual weight management related to reflux may indicate a more serious underlying condition and should be evaluated by your GP. Do not rely on reflux for weight management—it's not safe or sustainable.
What's the difference between reflux-related weight loss and prescribed weight loss medication?
Reflux-related weight loss is often unintentional and may signal a health problem. Prescription weight loss medications like Mounjaro and Wegovy are clinically designed and tested to support intentional, sustainable weight loss in eligible adults. They work through specific hormone mechanisms and require medical oversight, unlike passive weight loss from illness.
Who is eligible for prescription weight loss medication in the UK?
Adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (such as high blood pressure, type 2 diabetes, or cardiovascular disease) may be eligible. Eligibility is assessed individually by a prescriber following a clinical assessment. Ethnicity-specific thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults.
How much weight can I expect to lose with Mounjaro or Wegovy?
Clinical trials showed Mounjaro helped participants lose an average of 15–21% of body weight, while Wegovy supported average weight loss of around 15% of body weight. However, individual results vary significantly depending on dose, lifestyle adherence, genetics, and personal factors. Calculate your personal projection using our free weight loss calculator above.
Should I see my GP before starting prescription weight loss medication?
Yes. If you have acid reflux or any other health condition, inform your GP before starting any prescription medication. If accessing through the NHS, a referral to specialist services is typically required. If using private prescribing, a clinical assessment with a licensed prescriber is mandatory to ensure the medication is safe and appropriate for you.
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.