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 Should I Eat On Mounjaro?
When you start Mounjaro (tirzepatide), your appetite naturally changes, and food choices matter. This guide explains what to eat on Mounjaro aligned with NHS weight management principles, how to manage nausea and appetite changes, and which foods work best alongside this prescription injection. Individual responses vary, so talk to your GP or dietitian for personalised advice specific to your health.
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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.
Dietary Approach On Mounjaro — NHS Principles
Mounjaro works by reducing hunger and supporting a feeling of fullness, which means you'll naturally eat less. The best approach is to focus on nutrient-dense, whole foods rather than restrictive diets. NHS weight management guidance recommends:
- Lean proteins — chicken, fish, eggs, lentils, beans, tofu (help you feel satisfied longer)
- Whole grains — brown rice, wholemeal bread, oats, quinoa (provide sustained energy)
- Vegetables and fruit — aim for variety and colour (fibre supports digestion, which may be affected by Mounjaro)
- Healthy fats — olive oil, avocado, nuts in moderation (essential for nutrient absorption)
- Reduced-calorie drinks — water, tea, coffee, sugar-free options (stay hydrated)
Avoid ultra-processed foods, sugary snacks, and high-fat takeaways — not because they're "forbidden," but because they don't align with sustainable weight loss. Portion sizes naturally reduce on Mounjaro, so listen to your body's signals rather than forcing yourself to finish meals.
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.
Managing Side Effects Through Food Choices
Nausea and constipation are common on Mounjaro, especially when starting or increasing doses. Small, frequent meals often work better than three large ones. Eat slowly and chew thoroughly — rushing food increases nausea risk. Ginger tea, peppermint, or lemon water may help with nausea naturally.
Constipation is common because Mounjaro slows digestion. Increase soluble fibre gradually (oats, lentils, berries), drink plenty of water, and stay physically active. Avoid very greasy or heavy foods immediately after injections. If nausea persists beyond the first few weeks of a dose increase, speak to your GP — they may adjust your plan. Track your progress and food tolerance using our free progress tracker to identify patterns.
Work with your GP or NHS dietitian if available through your tier 3 weight management service. They can provide personalised meal planning, especially if you have type 2 diabetes or other health conditions. Private dietitians (HCPC-registered) are also available if NHS waiting lists are long. Your prescriber can also advise on medication interactions with oral medications — Mounjaro may reduce absorption of some tablets, so timing matters.
- 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 on Mounjaro?
Yes, but you'll naturally eat less. Mounjaro reduces appetite, so portions shrink automatically. Focus on nutrient-dense whole foods rather than processed options. Nausea in the first weeks may mean smaller meals feel better. Most people return to normal eating patterns (but smaller quantities) within 4 weeks of starting each dose.
What foods should I avoid on Mounjaro?
There are no forbidden foods, but avoid ultra-processed, sugary, or very fatty foods — they don't support weight loss and may trigger nausea. High-calorie takeaways also work against your weight loss goals. High-fibre foods are encouraged, but introduce them gradually to avoid digestive discomfort.
Does Mounjaro affect how I absorb nutrients from food?
Mounjaro slows gastric emptying (digestion speed), which may slightly affect nutrient absorption in the first weeks. Eating balanced meals with protein, whole grains, and vegetables ensures you get adequate nutrition despite smaller portions. If you're concerned about deficiencies long-term, discuss this with your GP or a registered dietitian.
Can I drink alcohol while taking Mounjaro?
Alcohol is not contraindicated with Mounjaro, but it may trigger or worsen nausea, especially in the first weeks. Alcohol is also calorie-dense and slows weight loss. If you do drink, do so moderately, eat food alongside it, and stay hydrated. Discuss personal alcohol use with your prescriber if concerned.
Should I count calories on Mounjaro?
Calorie counting isn't essential — Mounjaro naturally reduces intake. However, some people find loose tracking (using an app) helpful for awareness. The NHS recommends a balanced diet at a natural calorie deficit rather than strict counting. Use our GLP-1 weight loss calculator to set realistic expectations and monitor progress over time.
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.