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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What Diet Should You Follow When Taking Mounjaro?
When taking Mounjaro (tirzepatide) in the UK, diet is just as important as the medication itself. Mounjaro works best alongside a reduced-calorie diet and increased physical activity — the medication supports appetite control, but you still need to make intentional food choices. This guide explains what to eat, how to access Mounjaro in the UK, and the cost differences between NHS and private prescription routes. Whether you're exploring eligibility or already taking a Mounjaro KwikPen, understanding the dietary side will help you achieve the best results.
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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.
How to Diet Effectively While Taking Mounjaro
Mounjaro is most effective when combined with a structured approach to eating. You should aim for a calorie deficit of around 500 kcal per day, which typically results in losing approximately 0.5 to 1 kg per week — the NHS-recommended safe rate of weight loss. Focus on whole foods: lean proteins, vegetables, whole grains, and healthy fats. Many people on Mounjaro find their appetite naturally reduced, which can make portion control easier.
Practical dietary tips whilst on Mounjaro:
- Eat protein at every meal — it keeps you fuller longer and supports muscle preservation during weight loss
- Drink plenty of water — often people mistake thirst for hunger, and staying hydrated helps manage appetite
- Eat slowly and chew thoroughly — Mounjaro slows gastric emptying, so you may feel uncomfortably full if you eat too quickly
- Avoid high-fat, high-sugar foods — these can trigger nausea and stomach discomfort
- Keep a food diary — tracking what you eat helps identify patterns and keeps you accountable
Use our free GLP-1 weight loss calculator to estimate how much weight you might lose at your current dose alongside your dietary changes — results vary, but most people see measurable progress within 4 to 8 weeks when diet is consistent.
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 — NHS vs Private Cost
NHS route: Mounjaro is available through NHS tier 3 specialist weight management services, but access is limited and varies significantly by region. Your GP can refer you, though waiting lists can be lengthy (months to years in some areas). Once approved, NHS prescriptions are standard cost (currently around £9.65 per item in England). However, not all NHS regions have Mounjaro available — some still use Wegovy or older GLP-1 options.
Private prescription route: Private online consultations with UK-licensed prescribers typically cost £30–£50. If approved, Mounjaro dispensed through GPhC-registered pharmacies costs approximately £120–£200 per month depending on your dose. A Mounjaro KwikPen contains four weekly injections, and costs increase at higher dose levels. Private access means no NHS referral needed and faster access — usually within days.
Most people on private prescriptions choose this route for speed and accessibility, though cost is the trade-off compared to the NHS.
- 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 eat normally while taking Mounjaro?
You can eat normal foods, but portion sizes will likely be smaller — Mounjaro suppresses appetite. Most people find they naturally eat less without feeling deprived. However, combining this appetite suppression with intentional healthy choices (lean proteins, vegetables, whole grains) gives the best weight loss results. Avoiding high-fat and sugary foods also reduces nausea risk.
How much does Mounjaro cost on the NHS vs private in the UK?
NHS prescriptions cost the standard prescription charge (£9.65 in England), but access is limited and regional. Private prescriptions cost £30–£50 for the consultation, then £120–£200 per month for the medication depending on dose. Private access is faster but involves ongoing costs, while NHS access is cheaper but often involves long waiting lists.
What is the difference between Mounjaro KwikPen and Wegovy for diet and weight loss?
Both are once-weekly injections that support weight loss alongside diet. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist. Clinical trials show Mounjaro may result in slightly higher average weight loss (~20% body weight vs ~15% for Wegovy), but both work best with dietary changes. Eligibility and cost are similar in the UK.
How do I get Mounjaro prescribed privately in the UK?
You book an online consultation with a UK-licensed prescriber through a GPhC-registered online pharmacy or telehealth service. The prescriber reviews your medical history and BMI eligibility (typically BMI ≥30 or ≥27 with weight-related health conditions). If approved, a prescription is issued and the medication is dispensed within days. No NHS referral is needed.
Will my appetite come back once I stop taking Mounjaro?
Mounjaro's appetite-suppressing effects typically fade within days or weeks of stopping the medication. Some people maintain weight loss through the dietary habits and exercise routines they built whilst on the medication, but weight regain is common if diet and activity levels return to previous patterns. This is why sustainable lifestyle changes alongside the medication are important.
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.