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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Stomach Procedures For Weight Loss in the UK
Stomach procedures are surgical interventions designed to reduce stomach capacity or alter how food is digested, helping people achieve significant weight loss. In the UK, these are typically considered as part of the NHS weight management pathway for adults with severe obesity or significant weight-related health conditions. Common procedures include gastric bypass, gastric sleeve, and lap-band surgery. This guide explains how they work, who may be eligible, and how they fit within UK weight loss options—from medication to 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.
Types of Stomach Procedures Available in the UK
Gastric bypass is the most common bariatric surgery in the UK. It creates a small pouch from the stomach and connects it directly to the small intestine, bypassing most of the stomach. This reduces both the amount of food you can eat and the calories your body absorbs. Gastric sleeve surgery involves removing about 80% of the stomach, leaving a banana-shaped pouch. It reduces stomach capacity and may also affect appetite hormones. Lap-band surgery places an adjustable band around the upper stomach, creating a smaller pouch above it. It's less common now but still available. Duodenal switch is a more complex procedure combining gastric sleeve with intestinal bypass. All these are performed via keyhole (laparoscopic) surgery in most UK NHS trusts, reducing recovery time compared to open surgery.
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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.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Eligibility, Risks, and NHS Access
You may be considered for stomach surgery through the NHS if you have a BMI of 40 or above, or a BMI of 35 or above with weight-related health conditions like type 2 diabetes or sleep apnoea. You must have tried other weight management approaches first—including lifestyle changes and, where appropriate, medication. Bariatric surgery carries risks including infection, blood clots, nutrient deficiencies, and gallstones. Recovery takes 2–4 weeks. Long-term, you'll need to follow dietary guidelines and may need vitamin supplements for life. NHS waiting lists for bariatric surgery vary significantly by region. Consider using our free BMI calculator and GLP-1 weight loss calculator to understand your options within the broader weight management pathway.
- 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.
How much weight can you lose with stomach surgery?
Average weight loss is 50–70% of excess body weight within 2 years, depending on the procedure type and individual factors. Gastric bypass typically achieves more weight loss than lap-band surgery. Results vary significantly. Weight loss requires sustained dietary changes and physical activity alongside surgery.
Are stomach procedures available on the NHS in the UK?
Yes. Bariatric surgery is available on the NHS for eligible adults through specialist tier 4 weight management services. You typically need a BMI of 40+, or 35+ with weight-related health conditions, and must have tried other approaches first. Waiting lists vary by region and can be lengthy.
What's the difference between stomach surgery and weight loss injections like Mounjaro or Wegovy?
Stomach procedures are surgical interventions producing significant, permanent structural changes; average weight loss is 50–70% of excess weight. Mounjaro and Wegovy are non-surgical medications with average weight loss of 15–21%. Surgery is typically considered when other methods have not worked or when BMI is very high.
Do you need to take supplements after stomach surgery?
Yes. Bariatric surgery reduces the stomach's ability to absorb nutrients, so lifelong vitamin and mineral supplementation is usually necessary, including B12, iron, calcium, and vitamin D. Your surgical team will provide specific guidance and monitoring.
Can you regain weight after stomach surgery?
Weight regain is possible if dietary habits return to pre-surgery patterns, though the reduced stomach capacity makes this less likely than with medication alone. Long-term success requires sustained lifestyle changes, regular follow-up with your surgical team, and ongoing dietary discipline.
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.