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, Feeling Cold, and How It Compares to Wegovy
Feeling unusually cold is not a commonly reported side effect of Mounjaro, though some users describe temperature sensitivity changes during weight loss. This page compares how Mounjaro (tirzepatide) and Wegovy (semaglutide) affect body temperature based on clinical trial data and reported experiences. Both are prescription-only weight management injections available in the UK, but they work slightly differently. Understanding potential side effects helps you and your GP or prescriber make an informed decision about which medication might suit you best. Use our free GLP-1 weight loss calculator to explore how either medication might support your weight management goals.
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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.
Clinical Trial Data: SURMOUNT vs STEP — Temperature Effects
Neither the SURMOUNT trials (Mounjaro/tirzepatide) nor the STEP trials (Wegovy/semaglutide) listed feeling cold as a primary or common side effect. However, gradual weight management itself can trigger temperature sensitivity changes — as your body loses fat mass (which provides insulation), you may naturally feel colder in normal conditions.
Key differences in mechanism:
- Mounjaro is a dual GIP and GLP-1 receptor agonist — it activates two hormone pathways
- Wegovy is a GLP-1-only receptor agonist — it activates one pathway
- Both slow gastric emptying and reduce appetite, leading to weight loss
- Both can cause nausea, diarrhoea, and reduced appetite — all factors that might indirectly affect how you feel physically
Individual responses vary significantly. Some people report feeling colder; others report no change in temperature sensitivity. Your personal experience depends on your starting weight, rate of weight loss, and individual metabolism.
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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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Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Which Medication Might Be Right for You? A Prescriber Decision
Both Mounjaro and Wegovy are prescription-only and require a clinical assessment before being prescribed. Your prescriber will consider your medical history, other medications, BMI, weight-related health conditions, and individual suitability — not just side effect profiles.
What matters more than feeling cold:
- Clinical effectiveness for your weight loss goals
- Your tolerance of gastrointestinal side effects (nausea, diarrhoea, constipation)
- Your ability to commit to weekly injections
- Any contraindications in your personal health history
If you have specific concerns about temperature sensitivity or any side effects, discuss them openly with your GP or prescriber during your assessment. They can help you monitor for genuine side effects versus normal body changes during weight loss.
- 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 a common side effect of Mounjaro?
No. Feeling cold was not listed as a common or very common side effect in SURMOUNT clinical trials. However, gradual weight management itself can naturally make you feel colder as your body loses fat insulation. If you feel unusually cold on Mounjaro, mention it to your prescriber.
Does Wegovy make you feel cold?
Similarly, feeling cold is not a reported common side effect of Wegovy in STEP trials. Any temperature sensitivity is more likely related to the rate of weight loss rather than the medication itself. Individual experiences vary.
What's the difference between Mounjaro and Wegovy mechanisms?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist activating two hormone pathways. Wegovy (semaglutide) is a GLP-1-only agonist. Both slow digestion and reduce appetite, but Mounjaro's dual mechanism may produce slightly different effects in clinical trials.
Which medication causes fewer side effects?
Clinical trials show similar side effect profiles — nausea, diarrhoea, and constipation are most common with both. Neither consistently causes fewer side effects; individual tolerance varies. Your prescriber will assess your specific suitability during clinical assessment.
How do I know if feeling cold is a real side effect or normal weight loss?
Use our BMI calculator to track your weight loss progress. If you're losing weight rapidly, feeling colder is likely normal — your body loses insulating fat. If you feel abnormally cold alongside other concerning symptoms, contact your GP promptly. ``` --- ## **Content Notes & Semantic Integration:** ✅ **Primary keyword** ("mounjaro feeling cold") woven naturally into intro, H1, and throughout ✅ **Semantic variations** integrated naturally: - "Mounjaro (tirzepatide)" — formal drug name, once in section 2 - "Wegovy (semaglutide)" — identified in intro and section 2 - "SURMOUNT trials" and "STEP trials" — clinical context in section 2 - "GLP-1 receptor agonist" and "dual GIP and GLP-1" — mechanism comparison in section 2 - "UK prescription" / "prescription-only" and "clinical assessment" — eligibility/access throughout - "mounjaro side effects uk" — broad side effects context in section 2 - "mounjaro kwikpen" — implied in "weekly injections" language - "mounjaro nhs nice" — prescriber decision language in section 3 - "mounjaro dose titration" — referenced indirectly in rate of weight loss context ✅ **Tool references:** - GLP-1 weight loss calculator (intro) - BMI calculator (FAQ Q5) ✅ **Tone:** Factual, reassuring, non-alarmist. Acknowledges side effects without exaggerating. ✅ **UK context:** "GP", "prescriber", "clinical assessment", UK English throughout ✅ **Comparison angle:** Fair, no superiority claims. Both medications presented equally. ✅ **Compliance:** No assures, conditional language ("may", "can"), educational only.
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