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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Diet Plan on Mounjaro in the UK
Mounjaro (tirzepatide) is a prescription-only weight loss injection available through NHS specialist services and private prescribing in the UK. If you're taking Mounjaro, a structured diet plan alongside the medication can significantly improve your results. Unlike restrictive fad diets, an effective Mounjaro diet plan focuses on balanced nutrition, smaller portions, and foods that work well with how the medication affects your appetite and digestion. This guide covers practical dietary advice, what to expect when eating on Mounjaro, and how NHS services can support your weight loss journey.
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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 Diet Works With Mounjaro Treatment
Mounjaro works by activating GIP and GLP-1 hormone pathways, which reduce appetite and help you feel fuller after eating smaller meals. Because of this dual mechanism, your diet plan should complement these effects rather than fight against them. The medication slows gastric emptying—how quickly food leaves your stomach—which means you'll naturally eat less and feel satisfied longer.
Your diet plan on Mounjaro should include:
- Lean proteins (chicken, fish, eggs, tofu) — help maintain muscle during weight loss and support satiety
- Plenty of vegetables — low calorie, high fibre, reduce nausea risk
- Whole grains in small portions — provide sustained energy without large calorie spikes
- Healthy fats in moderation — avocado, olive oil, nuts (watch portions as they're calorie-dense)
- Adequate hydration — 1.5–2 litres daily, especially important as Mounjaro can cause nausea and constipation
Most people on Mounjaro find their appetite naturally suppressed, so restrictive dieting is unnecessary and can be counterproductive. Focus on nutrient-dense foods rather than calorie counting. As your dose increases from 2.5 mg to 15 mg over several weeks, your food tolerance may change — adjust your plan flexibly.
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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.
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NHS Support and Private Prescribing for Mounjaro Diet Plans
If you're accessing Mounjaro through NHS specialist tier 3 services, your weight management team should provide dietary guidance alongside your prescription. NHS services typically offer behavioural support and may refer you to a registered dietitian. However, NHS availability varies significantly by region, and waiting lists can be lengthy in many areas.
If you're using private prescribing, you won't automatically receive dietitian support—many private providers offer optional add-on nutritional consultations for an additional fee. Regardless of your route, use our free GLP-1 weight loss calculator to project your expected weight loss, and our progress tracker to log your dietary changes and weight over time. Most people on Mounjaro see results between 15–clinically studied weight loss over 68 weeks when combining the injection with modest dietary changes.
- 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.
What foods should I avoid on Mounjaro?
There are no foods you must completely avoid. However, limit very fatty foods, high-sugar items, and large meals, as these can worsen nausea and cause digestive discomfort. Many people on Mounjaro naturally avoid these anyway due to reduced appetite. Start with small portions and add back foods gradually as you assess tolerance. Your GP or dietitian can advise on your specific situation.
Can I eat normally on Mounjaro?
Not quite—portion sizes typically reduce dramatically on Mounjaro because the medication suppresses appetite. Many people find they eat 50–60% less naturally. This isn't enforced restriction; it's your body signalling it's satisfied sooner. This is actually the mechanism that drives weight loss. Focus on eating when genuinely hungry rather than following rigid meal schedules.
How quickly will I see weight loss results?
Clinical trials (SURMOUNT-1) showed average weight loss of 15–21% body weight over 68 weeks on Mounjaro, alongside a reduced-calorie diet and increased activity. Individual results vary significantly. Most people see measurable loss after 4–8 weeks, with the rate accelerating as doses increase. Our GLP-1 weight loss calculator can estimate your potential results based on your starting weight.
What should I eat if Mounjaro makes me feel sick?
Nausea is common, especially during dose increases. Eat smaller, more frequent meals. Choose bland, easily digestible foods: plain chicken, rice, toast, crackers, and broth-based soups. Avoid greasy and spicy foods temporarily. Drink plenty of water. Nausea usually reduces as your body adjusts to each dose. Contact your prescriber if it persists beyond two weeks at the same dose.
Do I need to join a specific diet programme while on Mounjaro?
No specific diet programme is required. You can use any approach—calorie counting, low carbohydrate, Mediterranean diet, or intuitive eating. What matters is maintaining a modest calorie deficit alongside the medication's appetite suppression. Some people prefer structure; others succeed with flexible portion control. Your GP or a registered dietitian can recommend an approach suited to your lifestyle.
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.