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
What Supplements Should I Take With Mounjaro?
When taking Mounjaro (tirzepatide) for weight management, you may wonder whether supplements are necessary or safe. The answer depends on your individual health, current diet, and what your prescriber recommends. While Mounjaro can reduce appetite and change how your body absorbs certain nutrients, supplementation isn't automatically required for everyone. Always discuss any supplements with your GP or the prescriber managing your Mounjaro treatment, as some can interact with medication or affect how well it works.
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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.
Key Nutrients to Consider With Mounjaro Treatment
Because Mounjaro slows stomach emptying and may reduce overall food intake, some people experience reduced nutrient absorption or deficiency risk—particularly vitamin B12, iron, and calcium. However, this is individual and depends on your diet quality and baseline nutritional status.
- Vitamin B12: Essential for energy and nerve health. Some people on weight loss medications benefit from B12 monitoring or supplementation, though evidence is not conclusive. Your GP can check levels via blood test.
- Iron: Reduced intake may affect some people, especially women. Iron-rich foods (red meat, leafy greens, lentils) are preferable to supplements unless deficient.
- Calcium and vitamin D: Important for bone health during weight loss. Ensure adequate dairy, fortified plant drinks, or supplements if dietary intake is low.
- Multivitamins: A standard multivitamin may be reasonable if your diet is very restricted, but discuss with your prescriber first.
Before starting any supplement, inform your prescriber. Some supplements can slow gastric emptying further, affecting Mounjaro's efficacy or increasing side effects.
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.
Accessing Mounjaro in the UK: Cost and Route Options
Mounjaro is available in the UK through two main routes: NHS specialist weight management services and private prescription via online prescribers. NHS access typically requires GP referral to a tier 3 or tier 4 weight management service, though availability varies significantly by region and waiting times can be lengthy. Private prescriptions are processed faster but involve out-of-pocket costs.
Each Mounjaro KwikPen contains four weekly doses. Private costs typically range from £129–£320 per month depending on dose and provider. Your prescriber will assess supplement needs alongside your prescription, so open communication about any products you're already taking is essential.
- 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.
Will Mounjaro affect my ability to absorb supplements?
Mounjaro slows gastric emptying, which may reduce nutrient absorption for some people. However, the effect varies significantly. If you have existing deficiencies or take supplements, mention this to your prescriber. They may recommend blood tests to monitor B12, iron, and other key nutrients during treatment.
Can I take a multivitamin with Mounjaro?
Generally yes, but timing matters. Some prescribers recommend taking multivitamins separately from Mounjaro injections to avoid interactions. Take multivitamins with food if possible, and always inform your prescriber about any supplements you use before starting Mounjaro treatment.
Is there a risk of vitamin deficiency on Mounjaro?
Risk depends on your diet quality and baseline health. If you eat a balanced diet with adequate protein, fruits, and vegetables, deficiency is less likely. However, very restrictive eating or gradual weight management can increase risk. Your GP can check nutrient levels via blood tests if concerns arise.
How do I get Mounjaro prescribed in the UK?
Either ask your GP for referral to NHS specialist weight management services, or access private prescription through a UK-licensed online prescriber following a clinical assessment. NHS access is free but may involve waiting lists; private access is faster but involves costs, typically £129–£320 monthly depending on dose.
Should I use the GLP-1 calculator before getting Mounjaro prescribed?
Yes—try our free GLP-1 weight loss calculator on this page to understand projected results and dosing. This gives you context before your clinical assessment. Your prescriber will also discuss realistic expectations, as individual results vary significantly and depend on diet, activity, and adherence.
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.