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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Gastric Balloon For Weight Loss — How It Works
A gastric balloon is an inflatable device placed in your stomach to help with weight management by reducing how much you can eat. It's one of several weight loss options available in the UK, alongside prescription weight loss medication and lifestyle changes. This guide explains what a gastric balloon is, how it works, who can have one, and how it compares to other weight management approaches like GLP-1 injections. Understanding all your options helps you and your GP decide what's right for your individual health needs.
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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.
What Is A Gastric Balloon And How Does It Work?
A gastric balloon is a soft, silicone balloon that's inserted into your stomach through your mouth (endoscopically) and then filled with saline solution. It takes up space in your stomach, which means you feel fuller after eating smaller amounts of food. This naturally reduces your appetite and helps you eat less without requiring surgery.
- Placement: The procedure takes 15–20 minutes under sedation. A flexible tube (endoscope) guides the deflated balloon into your stomach, where it's inflated and the tube is removed.
- Duration: Gastric balloons typically stay in place for 6 months, after which they're removed endoscopically.
- How it helps: By creating a feeling of fullness, it supports reduced calorie intake and can help you develop healthier eating habits during those 6 months.
- Weight loss: Studies suggest average weight loss of 10–15 kg during the 6-month period, though individual results vary significantly.
Unlike weight loss injections such as Wegovy (semaglutide), which work through hormonal pathways, the balloon works purely through physical volume in the stomach.
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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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Gastric Balloon vs Weight Loss Injections — Key Differences
Gastric balloons and GLP-1 weight loss injections like Wegovy are both available in the UK but work differently. Gastric balloons provide temporary mechanical restriction, while prescription weight loss medications work through hormonal signals that reduce appetite and regulate blood sugar. Balloons require an endoscopic procedure; injections are self-administered weekly. Balloons last 6 months; medications can be continued long-term if clinically appropriate.
Neither approach assures weight loss. Both work best alongside reduced-calorie diet and increased physical activity. Your GP can help assess which option aligns with your health needs, BMI, and preferences. Use our free BMI calculator to check your starting point, and discuss weight management pathways with your healthcare provider.
- 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.
Is a gastric balloon available on the NHS in the UK?
Gastric balloon placement is rarely available on the NHS. Most patients access this procedure privately through specialist weight loss clinics. Costs typically range from £3,000–£6,000. NHS weight management services usually recommend lifestyle changes, prescription medications (like Wegovy or Mounjaro), or bariatric surgery before considering balloons. Check with your GP about local tier 3 specialist services.
What are the side effects of a gastric balloon?
Common side effects include nausea, vomiting, abdominal discomfort, and acid reflux in the first few weeks as your stomach adjusts. Most settle within 2–3 weeks. Serious complications are rare but can include balloon deflation, obstruction, or perforation. Your clinician will discuss all risks before the procedure and provide aftercare support.
Can you eat normally with a gastric balloon?
No. With a balloon in place, you'll feel full quickly and eat significantly smaller portions. Your dietitian will advise you on meal sizes, food types, and hydration. Most people adapt within a few weeks. After removal at 6 months, your stomach returns to normal size, and portion control becomes your responsibility.
How does a gastric balloon compare to Wegovy for weight loss?
Wegovy (semaglutide) is a prescription GLP-1 injection available privately or (on limited availability) through NHS services. Clinical trials show average weight loss of ~15% body weight. Gastric balloons typically result in 10–15 kg loss over 6 months. Wegovy is ongoing; the balloon lasts 6 months. Both require commitment to diet and exercise. Your prescriber can advise which suits your health profile.
What happens after the gastric balloon is removed at 6 months?
The balloon is endoscopically removed, and your stomach returns to normal. To maintain weight loss, you'll need to continue healthy eating and physical activity habits developed during the 6 months. Some people choose to have the balloon replaced; others transition to ongoing weight loss medication or lifestyle management. Discuss aftercare planning with your clinician.
Ready to take control of your weight loss journey?
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