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
Which Vitamins Should You Take With Mounjaro?
When taking Mounjaro (tirzepatide) for weight management, many people wonder whether they need to take additional vitamins or supplements. Because Mounjaro slows gastric emptying and can affect how your body absorbs nutrients, supporting your nutritional intake is important. This guide explains which vitamins may be worth considering, how to access Mounjaro in the UK through NHS or private routes, and what costs are involved so you can make an informed decision about this prescription weight loss treatment.
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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.
Vitamins and Supplements to Consider With Mounjaro
When taking Mounjaro, reduced appetite may mean you eat smaller meals, so ensuring adequate nutrient intake becomes more important. Key vitamins to discuss with your GP or prescriber include:
- B vitamins: Essential for energy metabolism and nerve function—may help counteract fatigue some people experience on Mounjaro
- Vitamin D: Many UK adults are deficient; important for bone health and immune function
- Iron: Particularly for women; reduced food intake can lower dietary iron
- Calcium: Critical alongside vitamin D to maintain bone density during weight loss
- Electrolytes: If experiencing nausea, diarrhoea, or vomiting, electrolyte balance matters
- Protein supplements: While not technically vitamins, ensuring adequate protein intake helps preserve muscle mass during weight loss
Always consult your prescriber before starting any supplement—some can interact with medications or affect how Mounjaro works. Your GP can order blood tests to check for specific deficiencies and recommend personalised supplementation.
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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.
Accessing Mounjaro in the UK: NHS vs Private Routes
Mounjaro is available in the UK through two main routes: NHS specialist services or private prescribing. NHS access requires referral to a tier 3 specialist weight management service from your GP, though waiting times and regional availability vary significantly. Private online consultations with UK-licensed prescribers offer faster access without NHS referral; costs typically range from £129–£320 monthly depending on your dose. Both routes require a clinical assessment to confirm you're eligible—a BMI of 30 or above, or 27–29.9 with weight-related health conditions like diabetes or high blood pressure. Use the GLP-1 weight loss calculator on this page to explore potential outcomes, and speak with your GP about which route suits your circumstances.
- 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.
Do I need to take vitamins while on Mounjaro?
Not necessarily everyone, but it's worth discussing with your prescriber. Mounjaro reduces appetite, which may lower food intake and nutrient absorption. Blood tests can reveal deficiencies. Common supplements include B vitamins, vitamin D, iron, and calcium. Your GP can recommend personalised supplementation based on your individual needs.
Can vitamins interact with Mounjaro?
Some supplements may interact with Mounjaro or affect how it works. Always inform your prescriber of any vitamins or supplements you're taking. Fat-soluble vitamins (A, D, E, K) and certain minerals may be absorbed differently on Mounjaro due to slowed gastric emptying, so timing and dose matter.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £129–£320 per month depending on your dose. Starting doses (2.5–5mg) are usually cheaper; higher maintenance doses (10–15mg) cost more. Prices vary slightly between providers. NHS access is free but involves longer waiting times and requires specialist referral.
What's the difference between NHS and private Mounjaro access?
NHS requires GP referral to a tier 3 specialist service; regional availability and waiting times vary significantly. Private access is faster—you can consult with a UK-licensed prescriber online without NHS referral—but costs apply. Both require clinical assessment. Ask your GP about your local NHS options first.
Is tirzepatide the same as Mounjaro?
Yes. Tirzepatide is the active ingredient; Mounjaro is the brand name. Both refer to the same prescription weight management injection. It's a dual GIP and GLP-1 receptor agonist, making it different from Wegovy (semaglutide), which is a GLP-1 agonist only.
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.