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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Reflux and Weight Loss — How They're Connected
Reflux (acid reflux or gastro-oesophageal reflux disease, GORD) and weight are closely connected. Extra weight can increase pressure on the stomach, making reflux worse. Conversely, some weight loss medications used in the UK—including GLP-1 injections like Wegovy and Mounjaro—can cause reflux as a side effect. Understanding this relationship helps you make informed decisions about weight management and when to seek GP support for either condition.
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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.
How Weight Affects Reflux Symptoms
Carrying excess weight, particularly around the stomach area, increases intra-abdominal pressure. This pressure pushes the stomach contents upward, weakening the lower oesophageal sphincter (the valve that prevents acid from rising into the oesophagus). Research shows that losing even 5–10% of body weight can significantly improve reflux symptoms.
- Higher BMI = increased reflux risk: Adults with a BMI of 25 or above have a higher incidence of GORD
- Waist circumference matters: Excess stomach fat is a stronger predictor of reflux than overall weight
- Weight loss benefits: Shedding weight through lifestyle changes (diet and exercise) often reduces reflux without medication
For UK weight management, using our free BMI calculator can help you understand whether your current weight is contributing to reflux symptoms. If you're overweight (BMI 25–29.9) or obese (BMI 30+), even modest weight loss may ease reflux.
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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.
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GLP-1 Weight Loss Medications and Reflux
Wegovy (semaglutide) and Mounjaro (tirzepatide) are prescription-only GLP-1 weight loss injections available in the UK. These medications help with weight loss, but reflux is a common side effect, particularly during the initial weeks or when increasing doses.
- Why it happens: GLP-1 medications slow gastric emptying (how quickly food leaves the stomach), which can increase reflux risk temporarily
- Typical timing: Reflux symptoms often improve as your body adjusts to the medication (usually within 4–8 weeks)
- Management: Your prescriber may recommend lifestyle adjustments—eating smaller meals, avoiding trigger foods, sleeping upright—or temporary antacid use
If reflux is severe or worsens on weight loss medication, always inform your GP or prescriber. They can assess whether adjustments are needed.
- 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 weight loss supports reflux?
Weight loss can significantly improve reflux symptoms, especially if excess weight is a contributing factor. Losing 5–10% of body weight often reduces symptoms. However, reflux can have other causes (dietary, genetic, medication-related), so it may not completely resolve without addressing those factors too. Consult your GP for personalised advice.
Will Wegovy or Mounjaro make my reflux worse?
Both medications can cause reflux as a side effect because they slow stomach emptying. This often improves within weeks as your body adjusts. If reflux is severe, tell your prescriber—they may suggest eating smaller meals, avoiding trigger foods, or taking antacids. Dose adjustments are sometimes needed, but don't stop medication without medical guidance.
What's the best way to lose weight if I have reflux?
Gradual weight loss through a balanced, reduced-calorie diet and increased physical activity is ideal for reflux sufferers. Avoid large meals, acidic foods, and eating close to bedtime. The NHS recommends losing 0.5–1 kg per week. For structured support, ask your GP about tier 3 weight management services or discuss prescription options if eligible.
How does reflux affect BMI calculations?
Reflux doesn't change how BMI is calculated—BMI is purely based on weight and height. However, reflux symptoms may improve once you're in a healthier BMI range (18.5–24.9 for most adults). Use our free BMI calculator to check your current status and discuss weight targets with your GP.
Should I wait until reflux improves before starting weight loss treatment?
Not necessarily. Many people manage both reflux and weight loss simultaneously. If you're overweight and reflux is worsening your quality of life, losing weight (through diet, exercise, or prescription medication) can help both conditions. Discuss your options with your GP or a specialist weight management service to find the safest approach 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.