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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Latest Weight Loss Pills Available in the UK
The latest weight loss pills available in the UK are prescription-only GLP-1 and GIP/GLP-1 receptor agonist medications that work differently from older weight loss drugs. These include Wegovy (semaglutide), Mounjaro (tirzepatide), and Saxenda (liraglutide) — all licensed for weight management in UK adults. Unlike older appetite suppressants, these newer medications work with your body's natural hormones to reduce hunger and support feeling fuller after smaller meals. Access is through NHS specialist weight loss services or private prescribing following a clinical assessment. Understanding how these latest weight loss medications work, who can take them, and what results to expect can help you make informed decisions about your weight management options.
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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 the Latest Weight Loss Medications Work
The newest weight loss pills licensed in the UK are GLP-1 receptor agonist injections — a class of medication that mimics a natural gut hormone called glucagon-like peptide-1 (GLP-1). This hormone regulates appetite, blood sugar, and how quickly food leaves your stomach.
- Wegovy (semaglutide) — A once-weekly injection that activates the GLP-1pathway. In clinical trials (STEP-1), participants taking 2.4 mg lost an average of 14.9% of their body weight over 68 weeks alongside a reduced-calorie diet and increased physical activity.
- Mounjaro (tirzepatide) — The latest innovation, a once-weekly injection that activates both GIP and GLP-1 pathways (dual agonist). The SURMOUNT-1 trial showed average weight loss of 15–21% depending on dose.
- Saxenda (liraglutide) — A daily injection with a slightly longer track record. Average weight loss is typically 5–10% of body weight.
All work alongside a reduced-calorie diet and increased physical activity — they are not replacements for lifestyle changes. Individual results vary significantly based on genetics, lifestyle adherence, and starting weight.
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.
Eligibility, Access, and What to Expect
In the UK, prescription weight loss medication eligibility includes adults with a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. For South Asian, Chinese, Black African, and Black Caribbean adults, lower thresholds apply due to higher health risks at these BMI levels. You can use our free BMI calculator to check your personal BMI, then discuss options with your GP. Access through NHS specialist weight management services varies by region — waiting lists can be lengthy. Private prescribing is also available through GPhC-registered online pharmacies following a clinical assessment, offering faster access but at private cost (typically £129–£320 monthly depending on dose). Weight loss is not assured — these medications may help, but results depend on sustained dietary changes, physical activity, and individual response. Track your progress using our free progress tracker to monitor results over time.
- 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.
What's the difference between Wegovy and Mounjaro?
Both are once-weekly injections for weight loss. Wegovy (semaglutide) activates the GLP-1 pathway; Mounjaro (tirzepatide) activates both GIP and GLP-1 pathways (dual action). Mounjaro is newer. Clinical trials show similar or slightly higher average weight loss with Mounjaro, but individual results vary. Both require prescription and clinical assessment.
Are these weight loss pills covered by the NHS?
Yes, Mounjaro and Wegovy are available through NHS specialist tier 3 weight management services for eligible adults. However, availability and waiting times vary significantly by region and local integrated care boards. Your GP can refer you for assessment. Private prescribing is an alternative route that doesn't require NHS referral.
What side effects do the latest weight loss medications cause?
Common side effects include nausea, diarrhoea, constipation, vomiting, and stomach pain — especially when starting or increasing doses. These often improve over time. Serious side effects are rare but include severe stomach pain (possible pancreatitis) and gallbladder problems. Always inform your prescriber of all medications, as GLP-1s may reduce absorption of oral contraceptives and other drugs.
How quickly will I lose weight on these medications?
Clinical trial data shows average weight loss of 14.9–20.9% of body weight over 68–72 weeks alongside dietary changes and exercise. However, weight loss is highly individual — some people lose more, others less. The NHS recommends losing 0.5–1 kg per week for sustainable results. Use our GLP-1 weight loss calculator to estimate potential outcomes based on your characteristics.
Can I get these weight loss pills from a standard GP prescription?
Not typically — most GPs refer eligible patients to specialist tier 3 weight management services where these medications are prescribed. Some private GP services can prescribe, but this requires a private fee and clinical assessment. Your GP can advise on options available in your area. Prescription weight loss medication is never available over-the-counter in the UK.
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.