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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Weight Loss and Heart Failure — UK Medication Options
If you have heart failure and are overweight, weight management can significantly improve your health outcomes. Several prescription weight loss medications are now available in the UK for eligible adults, often prescribed alongside lifestyle changes and medical treatment. This guide explains your options, NHS access routes, and how to have a conversation with your GP about prescription weight management suitable for your individual circumstances.
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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.
UK-Licensed Prescription Weight Loss Medications
Three prescription-only weight management medications are currently licensed in the UK and may be considered for eligible adults:
- Mounjaro (tirzepatide) — a once-weekly injection. Dual GIP and GLP-1 receptor agonist. Clinical trials showed average weight loss of 15–21% of body weight when combined with dietary changes and increased physical activity.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection. Clinical trial evidence demonstrates average weight loss of around 15% of body weight over 68 weeks on the maximum dose.
- Saxenda (liraglutide) — a once-daily GLP-1 injection, available since earlier than the once-weekly options. Average weight loss of 5–10% of body weight.
All three are prescription-only and require a clinical assessment to determine suitability. Individual results vary significantly. Each medication works by helping to reduce appetite, support feeling fuller after smaller meals, and may improve blood sugar control — particularly relevant for those with heart failure risk factors.
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.
NHS Access vs Private Prescription Routes
NHS route: Prescription weight loss medications may be available through NHS specialist tier 3 weight management services following GP referral. Availability varies significantly by region and ICB. Many areas have substantial waiting lists. Your GP can refer you if you meet eligibility criteria.
Private route: Available through GPhC-registered online prescribers following a confidential clinical assessment. No NHS referral required. Available more quickly in most cases. Costs vary by dose and provider (typically £129–£320 per month).
Whichever route you pursue, a licensed prescriber will assess your individual health, medications, and suitability before issuing a prescription. Weight loss medication is typically recommended alongside lifestyle changes, not instead of them. Our free GLP-1 weight loss calculator can help you understand potential weight loss projections at different doses.
- 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.
Can I take weight loss injections if I have heart failure?
Heart failure doesn't automatically exclude you from weight loss medications, but individual assessment is essential. A prescriber will review your specific type of heart failure, current medications, and overall health before deciding if Mounjaro, Wegovy, or Saxenda is appropriate. Some heart failure medications interact with GLP-1 medications, so medical review is critical. Always inform your prescriber of your heart failure diagnosis and current treatments.
How much weight can I expect to lose with prescription medication?
In clinical trials, GLP-1 and GIP/GLP-1 medications helped participants lose on average 15–21% of body weight over 15–18 months, alongside reduced-calorie diet and increased activity. Individual results vary considerably — some people lose more, others less. Weight loss depends on dose, adherence, lifestyle changes, and individual factors. Your prescriber will discuss realistic expectations during assessment.
What is the difference between Mounjaro and Wegovy for weight loss?
Mounjaro (tirzepatide) activates two hormone pathways (GIP and GLP-1), while Wegovy (semaglutide) activates only GLP-1. Both are once-weekly injections. Clinical trial data suggests Mounjaro may result in slightly greater average weight loss, but individual response varies. Choosing between them depends on your health, medications, tolerability, and prescriber recommendation following clinical assessment.
How do I know if I'm eligible for NHS weight loss medication?
NHS eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions (which may include heart failure-related complications like high blood pressure). However, availability and exact criteria vary by region. Start by speaking with your GP, who can assess your individual circumstances and refer you to specialist services if appropriate. Check your local ICB website for regional guidelines.
Can weight loss medication replace heart failure treatment?
No. Weight loss medications are prescribed alongside, not instead of, your existing heart failure medications and medical management. Weight management supports your overall health and may reduce strain on your heart, but it complements rather than replaces prescribed cardiac treatments. Always continue taking all prescribed medications unless specifically advised otherwise by your GP or cardiologist.
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.