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
Why Do You Feel Cold On Mounjaro?
Feeling cold is a known side effect some people experience when taking Mounjaro (tirzepatide), particularly during dose titration and active weight loss phases. This happens because your body is losing fat mass and your metabolism is adjusting to reduced calorie intake. Mounjaro is a prescription-only GIP and GLP-1 receptor agonist medication licensed in the UK for weight management in adults. Understanding this side effect and knowing how to access Mounjaro through NHS or private routes can help you make informed decisions about your weight management.
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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.
How Cold Sensitivity Works With Mounjaro
When you lose weight, your body naturally generates less internal heat because you have less body mass and less insulating fat tissue. Cold sensitivity on Mounjaro typically occurs because the medication causes significant weight loss, especially at higher doses like 10 mg and 15 mg, which can affect your body's thermoregulation. Additionally, reduced calorie intake slows your metabolism slightly, further lowering heat production. Most people find this effect is temporary and diminishes as their body adjusts to their new weight. Wearing additional layers, staying hydrated, and maintaining adequate protein intake can help manage this discomfort.
- Weight loss reduces insulating fat tissue, lowering body temperature
- Reduced calorie intake lowers metabolic rate temporarily
- The effect is usually most noticeable during the first 8–16 weeks of treatment
- Symptoms typically improve as your body adapts and stabilises at a lower weight
- Staying warm and maintaining nutrition can help
If persistent cold sensitivity affects your quality of life, speak to your GP or prescriber — they may adjust your dose or provide additional guidance.
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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.
Accessing Mounjaro in the UK: NHS vs Private
NHS access to Mounjaro is available through specialist tier 3 weight management services, but availability varies significantly by region and waiting lists can extend several months. Your GP can refer you if you meet eligibility criteria (BMI 30+ or 27–29.9 with weight-related health conditions). Private prescription routes offer faster access — you can complete an online consultation with a UK-licensed prescriber without NHS referral, though costs range from approximately £130–£300 per month depending on your dose. Both routes require a clinical assessment to confirm Mounjaro is suitable for you. Use our free GLP-1 weight loss calculator to estimate potential results, and our BMI calculator to check your starting point before beginning 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 feeling cold on Mounjaro dangerous?
Feeling cold is uncomfortable but not dangerous. It's a normal response to weight loss and reduced body mass. If you feel excessively cold or develop other concerning symptoms like uncontrollable shivering, contact your GP or prescriber for guidance.
How long does cold sensitivity last on Mounjaro?
Cold sensitivity usually peaks during active weight loss phases (typically weeks 4–16) and improves as your body adjusts to your new weight. Most people find it resolves within 2–3 months of stabilising their weight. Individual timescales vary.
Can I take Mounjaro on the NHS in the UK?
Yes, Mounjaro (tirzepatide) is approved on the NHS through specialist weight management services. Access is through tier 3 services via GP referral. However, availability and waiting times vary significantly by region — contact your local ICB or ask your GP about local access.
What's the difference between Mounjaro and Wegovy for weight loss?
Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) activates GLP-1 only. Clinical trials show both can support weight loss, though Mounjaro's dual mechanism may produce slightly greater average weight loss. Both require a prescription and clinical assessment.
How much does private Mounjaro cost per month in the UK?
Private Mounjaro costs typically range from £130–£300 per month depending on your dose (2.5 mg to 15 mg). Prices vary between private prescribing services. Always confirm the total cost, including any consultation fees, before starting treatment. NHS access is free if available in your region.
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.