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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Mounjaro and Feeling Hungry — What to Know
If you're on Mounjaro and still feeling hungry, you're not alone — this is a common question from people using tirzepatide for weight management. While Mounjaro works as a GIP and GLP-1 receptor agonist to reduce appetite and support feeling fuller after smaller meals, hunger doesn't always disappear completely, especially in the early weeks of treatment. This guide explains why hunger can occur during Mounjaro therapy, what's normal, and when to speak to your prescriber about your experience.
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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 Affects Hunger and Appetite
Mounjaro (tirzepatide) activates two natural hormone pathways — GIP and GLP-1 — that help regulate appetite and satiety signals in the brain. This dual mechanism means Mounjaro typically has a stronger appetite-suppressing effect than single GLP-1 medications like Wegovy (semaglutide). However, the strength of this effect varies between individuals.
During the early titration phase — when your dose increases every 4 weeks from 2.5 mg up to 15 mg — appetite suppression often builds gradually. Some people experience significant appetite reduction from week 1, whilst others take several weeks to notice a change. Hunger may also return slightly between weekly injections, particularly at lower doses. Feeling hungry does not mean Mounjaro isn't working; clinical trials showed that even participants who experienced some hunger still achieved substantial weight loss alongside dietary changes and increased physical activity.
Dose titration timing matters: Many people find that hunger is more noticeable during weeks 1–4 at the starting 2.5 mg dose. As you progress to 5 mg, 7.5 mg, 10 mg, 12.5 mg, and eventually 15 mg, appetite suppression typically becomes more pronounced — though this isn't assured.
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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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When to Speak to Your Prescriber About Hunger
If you're experiencing persistent, uncomfortable hunger that's affecting your ability to follow a reduced-calorie diet, discuss this with your prescriber. They may suggest waiting for your next dose increase, as hunger often reduces as the dose escalates. Your prescriber can also rule out other causes — such as dehydration, insufficient protein intake, or side effects like nausea that might mask appetite changes.
It's important to remember that Mounjaro is designed to work alongside lifestyle changes, not replace them. Eating nutrient-dense foods, staying hydrated, and incorporating regular physical activity all support appetite management. If hunger remains significant after reaching a stable dose, your prescriber may consider adjusting your dose, extending your time at your current dose, or discussing whether a different approach might be more suitable. Keep a food and hunger diary — this helps your prescriber understand your patterns and make informed decisions about your treatment.
- 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.
Is it normal to feel hungry while taking Mounjaro?
Yes. Mounjaro reduces appetite for most people, but hunger doesn't always disappear completely — especially at lower doses or early in treatment. Individual responses vary. Feeling some hunger between injections is normal. If persistent hunger prevents you following a reduced-calorie diet, discuss this with your prescriber.
Does hunger mean Mounjaro isn't working?
No. Clinical trials showed participants achieved significant weight loss whilst still experiencing some hunger. Mounjaro works alongside diet and activity changes, not by eliminating hunger completely. Your weight loss is the relevant measure of effectiveness, not how hungry you feel.
When does Mounjaro's appetite-suppressing effect start?
Many people notice reduced appetite within days of the first 2.5 mg dose, but it can take 2–4 weeks. The effect typically becomes stronger as you increase to higher doses over weeks 1–20. Some people notice appetite suppression most clearly after reaching their maintenance dose (usually 10–15 mg).
Should I eat more if I'm still hungry on Mounjaro?
No. Hunger on Mounjaro doesn't mean you need more food. Your prescriber has recommended a specific calorie deficit for weight loss. If you're struggling with hunger, speak to your GP or prescriber — don't increase calories without guidance, as this will slow weight loss progress.
Can hunger come back after a few weeks on Mounjaro?
Some people experience reduced appetite suppression after several months — this is sometimes called "appetite adaptation". This is normal. Your prescriber can discuss dose adjustments or other strategies. Using our free GLP-1 weight loss calculator can help you understand expected progress at different doses.
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.