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
Weight Loss With Diverticulitis: UK Medication Guide
Losing weight while managing diverticulitis requires careful planning and medical support. If you have diverticulitis and are overweight, prescription weight loss medication may be an option — but only under careful GP supervision. This guide explains which medications are available in the UK, eligibility criteria, and how to have the right conversation with your healthcare team about safe weight management alongside your digestive condition.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Prescription Weight Loss Options for Diverticulitis
Three GLP-1 and dual-action medications are currently licensed for weight management in the UK: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All three work by regulating appetite and helping you feel fuller after smaller meals.
For adults with diverticulitis, these medications require extra caution because they slow stomach emptying and can affect digestion. Saxenda (a daily injection) and Mounjaro or Wegovy (once-weekly injections) are only suitable if your GP confirms your diverticulitis is stable and well-managed. Eligibility requires a BMI of 30 or above, or 27+ with weight-related health conditions such as high blood pressure or type 2 diabetes. Individual clinical assessment is essential — your GP will evaluate your digestive history before any prescription.
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 available through NHS specialist weight management services (tier 3) or private online prescribing following a clinical assessment. NHS access typically requires a GP referral and can involve waiting lists; private options are faster but involve a cost. Before pursuing any medication, discuss your diverticulitis history with your GP — include how often you have flare-ups, current management, and any dietary restrictions. Your GP can refer you to a specialist if appropriate or discuss whether weight management through diet and exercise adjustments might be safer first.
Calculate your current BMI using our free BMI calculator to understand your starting point, and track progress with our free progress tracker once you have a plan in place.
- 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 I take weight loss injections if I have active diverticulitis?
No. Weight loss injections slow stomach emptying and digestion, which can worsen diverticulitis flare-ups. Your diverticulitis must be stable and well-controlled for months before these medications are considered. Your GP must assess your individual case first.
Which weight loss medication is safest with diverticulitis?
No single medication is definitively safest — it depends on your diverticulitis severity and stability. Wegovy and Mounjaro (once-weekly) may be preferable to Saxenda (daily) because they're less frequent doses. Your GP or specialist weight management service will recommend based on your full health picture.
Will the NHS prescribe weight loss medication if I have diverticulitis?
Possibly, but it's less straightforward than for patients without GI conditions. You'll need GP referral to a specialist weight management service (tier 3). The specialist will assess whether the benefits outweigh digestive risks. Access varies by region.
What should I tell my GP about my diverticulitis when asking about weight loss medication?
Share: frequency of flare-ups, how you manage them (diet, medication, surgery history), current symptoms, any dietary restrictions, and how your weight affects your overall health. Honesty helps your GP decide if medication is appropriate or if lifestyle changes should come first.
Is weight loss with diet and exercise safer than medication if I have diverticulitis?
For many people with diverticulitis, yes. Gradual weight loss through gentle dietary changes (high fibre during remission, avoiding triggers) and low-impact exercise may be safer than introducing medications that affect digestion. Discuss this option with your GP before assuming medication is necessary.
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.