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
Does Mounjaro Affect Sleep?
Sleep disturbances are not commonly reported as a direct side effect of Mounjaro in clinical trials, though some people may experience changes in sleep patterns related to other side effects or individual responses. Understanding how Mounjaro compares to Wegovy, and what the evidence actually shows, can help you make an informed decision if you're considering prescription weight loss treatment in the UK. Both medications work through similar hormone pathways but have different mechanisms, which may affect side effect profiles differently between individuals.
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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.
Mounjaro, Wegovy, and Sleep — What the Evidence Shows
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist approved for weight management in UK adults. In the SURMOUNT clinical trials that led to its UK approval, sleep disturbance was not listed as a common or very common side effect. The most frequently reported side effects were gastrointestinal — nausea, diarrhoea, vomiting, and constipation — particularly when starting or increasing doses.
Wegovy (semaglutide) is a GLP-1 receptor agonist only. Similarly, in the STEP clinical trials, sleep disturbance was not prominently reported as a direct side effect, though fatigue and dizziness were documented as common effects in some participants.
- Both medications may indirectly affect sleep through nausea or stomach discomfort, especially in the first few weeks
- Changes in appetite and eating patterns can sometimes influence sleep quality
- Individual responses vary significantly — some users report better sleep due to improved health, others may experience temporary disruption
- Sleep effects are not a reason to avoid either medication if clinically appropriate for you
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Individual Suitability and Next Steps
Whether Mounjaro or Wegovy is right for you depends on your individual health profile, not on theoretical sleep risks. A UK-licensed prescriber will assess your medical history, current medications, and weight-related health conditions to determine which medication — if either — is suitable.
Both medications are prescription-only and require a clinical assessment before being prescribed. Your GP can refer you to an NHS specialist weight management service, or you can access private prescribing through a GPhC-registered online pharmacy. Use our GLP-1 weight loss calculator to explore potential outcomes, and our BMI calculator to understand your current health context. A prescriber can then discuss the most appropriate option for your circumstances alongside lifestyle 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.
Does Mounjaro cause sleep problems?
Sleep disturbance is not listed as a common side effect of Mounjaro in clinical trials. However, some people may experience indirect sleep effects from nausea, stomach discomfort, or appetite changes, particularly when starting or increasing doses. These effects typically improve over time.
Is Wegovy better for sleep than Mounjaro?
There is no evidence that Wegovy is superior to Mounjaro regarding sleep. Both medications show similar low rates of sleep-related side effects in clinical trials. The choice between them depends on individual health factors assessed by your prescriber, not sleep concerns.
Can GLP-1 injections affect my sleep quality?
GLP-1 medications like Wegovy and the dual GIP/GLP-1 Mounjaro primarily affect appetite and digestion. Sleep quality may be indirectly influenced by gastrointestinal side effects or changes in eating patterns, but direct sleep disturbance is not a commonly reported effect.
How long before Mounjaro side effects improve?
Gastrointestinal side effects from Mounjaro typically improve within 2–4 weeks of starting or increasing your dose as your body adjusts. If side effects persist beyond 4 weeks, contact your prescriber. Sleep quality should not be significantly affected.
Should I avoid Mounjaro if I have sleep concerns?
Sleep concerns alone are not a reason to avoid Mounjaro if you are otherwise eligible and it is clinically appropriate for you. Discuss any existing sleep conditions with your prescriber during your clinical assessment — they will advise whether Mounjaro or Wegovy is suitable.
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.