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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How Much Do You Eat On Mounjaro?
One of the most common questions about Mounjaro is how much food you'll actually be able to eat whilst taking it. The answer varies significantly from person to person, but most people experience reduced appetite and feel fuller faster after eating smaller portions. Mounjaro works by activating two natural hormone pathways (GIP and GLP-1 receptors) that signal to your brain when you're satisfied, making it easier to eat less without feeling deprived. Your portion sizes will likely decrease naturally as the medication works, but the amount varies based on your individual response, dose, and lifestyle factors.
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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 Mounjaro Changes Your Appetite
Mounjaro (tirzepatide) is a prescription-only GIP and GLP-1 receptor agonist that mimics natural hormones responsible for appetite regulation and fullness signals. When you take Mounjaro, these hormone signals are amplified, meaning your brain receives "you're full" messages more quickly and strongly than usual.
- Most people report feeling satisfied after eating noticeably smaller portions
- Hunger and food cravings typically reduce, especially for calorie-dense or sugary foods
- The sensation of being full lasts longer, reducing the urge to snack between meals
- Some people experience reduced interest in food — a phenomenon often described as "appetite suppression"
The degree of appetite reduction varies widely. Some people on Mounjaro find they naturally eat 40–50% less food, whilst others experience a more modest reduction of 20–30%. Dose escalation affects this too — higher doses (10mg, 15mg) typically produce greater appetite reduction than starting doses (2.5mg, 5mg).
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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.
Typical Food Intake Changes on Mounjaro
In clinical trials (SURMOUNT-1), participants taking Mounjaro reported significant changes in eating patterns. Most people move from eating regular-sized meals to feeling comfortably full on considerably smaller quantities. For example, what might have been a normal dinner plate becomes satisfying as just half that amount.
- Breakfast: Often reduced from cereal + toast to just toast or a small bowl of porridge
- Lunch: Typically shrinks from a full sandwich to half, or a small salad with protein
- Dinner: Often becomes a normal-sized portion of protein and vegetables, where previously larger portions were eaten
- Snacking: Usually stops naturally — most people lose the desire to snack between meals
Important: You must still eat enough to meet your nutritional needs. Your GP can advise on maintaining adequate protein and micronutrient intake whilst on Mounjaro. Using our free GLP-1 weight loss calculator can help project your expected weight loss at your prescribed dose.
- 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 I feel hungry on Mounjaro?
Most people experience significantly reduced hunger on Mounjaro, especially at higher doses. However, some people retain some hunger signals, particularly in the first few weeks before reaching maintenance doses. Hunger typically decreases as your dose increases through the titration schedule (2.5mg → 5mg → 7.5mg → 10mg → 15mg).
How long does appetite suppression last on Mounjaro?
Appetite reduction begins within days to weeks of starting, and continues throughout your treatment. The effect is sustained as long as you take Mounjaro. If you stop taking it, appetite typically returns to normal within weeks. Some people find that healthier eating habits formed on Mounjaro persist afterwards.
Can I still enjoy food and socialise on Mounjaro?
Yes. Mounjaro reduces quantity and cravings but doesn't remove the ability to enjoy food. Many people report actually enjoying meals more because they're eating mindfully in smaller portions. Social eating is still possible — you'll simply eat less than previously whilst still feeling satisfied and included.
What if I can't eat enough on Mounjaro?
If you're struggling to eat adequate nutrition, contact your prescriber immediately. Very low food intake can lead to nutritional deficiencies and muscle loss. Your prescriber may adjust your dose or provide dietary guidance. This is why prescription Mounjaro includes clinical assessment and ongoing support.
Does appetite return to normal after stopping Mounjaro?
Yes. Appetite typically normalises within 2–4 weeks of stopping tirzepatide. However, many people find that the healthy eating habits and portion awareness developed during treatment remain beneficial. Some people maintain weight loss through lifestyle changes even after stopping the medication.
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.