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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How To Stop Bloating On Mounjaro — And How It Compares To Wegovy
Bloating is a common side effect when starting tirzepatide (Mounjaro), but there are practical steps to reduce it. This guide explains why bloating happens on Mounjaro, how it compares to Wegovy, and what you can do to manage it. If you're considering weight loss medication in the UK, understanding potential digestive side effects helps you make an informed decision alongside your prescriber. Both Mounjaro and Wegovy can cause temporary bloating as your body adjusts to the dual GIP and GLP-1 (or GLP-1-only) mechanism, but strategies exist to minimise discomfort.
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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.
Why Bloating Happens On Mounjaro vs Wegovy — Clinical Context
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist. The SURMOUNT clinical trials showed that bloating and abdominal discomfort are common in the early weeks because the medication slows gastric emptying—how quickly food leaves your stomach. This effect typically reduces over time as your body adapts. Wegovy (semaglutide) is a GLP-1-only agonist with a similar mechanism, and STEP trial data shows comparable rates of bloating and digestive side effects.
Both medications can cause:
- Temporary bloating and gas
- Stomach distension
- Feeling overly full quickly
- Indigestion or reflux
The key difference is that Mounjaro's dual mechanism may produce slightly different digestive patterns during the dose titration phase. Individual responses vary significantly. Your prescriber can assess which medication suits your digestive health profile best.
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If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
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Practical Steps To Manage Bloating On Either Medication
Start with small, frequent meals rather than three large ones. Eat slowly and chew thoroughly—this reduces air intake and aids digestion. Choose bland, low-fat foods initially; greasy or high-fibre foods can worsen bloating. Stay hydrated with water, but avoid fizzy drinks, which increase gas. Ginger tea, peppermint tea, or over-the-counter remedies like simethicone may help. Light walking after meals aids digestion. If bloating persists beyond 4–6 weeks or becomes severe, contact your GP—it may indicate you need a dose adjustment or the medication isn't suitable. Our free GLP-1 weight loss calculator can help you explore different dose scenarios and side effect profiles before discussing options with your prescriber.
- 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.
Does Mounjaro cause more bloating than Wegovy?
Clinical trial data shows comparable rates of bloating between Mounjaro and Wegovy. However, individual responses differ. Mounjaro's dual GIP+GLP-1 mechanism may affect digestion differently than Wegovy's GLP-1-only action. Your prescriber can discuss which is likely better suited to your digestive health based on your medical history.
How long does bloating last on Mounjaro?
Bloating is typically most noticeable in the first 2–4 weeks and often improves as your body adjusts. By weeks 8–12, many people experience significant improvement. If bloating persists beyond 6 weeks or worsens, speak to your prescriber—a dose adjustment or switch to an alternative may be appropriate.
Are there foods I should avoid while taking Mounjaro to reduce bloating?
Yes. Avoid high-fat, greasy, spicy, and very high-fibre foods initially. Fizzy drinks and artificial sweeteners can increase gas. Eat small portions, chew slowly, and choose bland options like plain chicken, rice, and vegetables. Gradually reintroduce normal foods as bloating improves.
Should I stop taking Mounjaro if bloating is severe?
Do not stop without consulting your GP. Severe bloating may indicate you need a dose adjustment, a slower titration schedule, or that the medication isn't suitable for you. Your prescriber can review your symptoms and recommend next steps—which might include switching to Wegovy or another option.
Can the Mounjaro KwikPen dose affect bloating severity?
Yes. Starting at the lowest dose (2.5 mg) and increasing gradually every 4 weeks allows your body to adjust. Rapid dose escalation can worsen bloating. Discuss your titration schedule with your prescriber if digestive symptoms are a concern—a slower increase may be better tolerated.
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