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
What Are T5 Weight Loss Pills?
T5 weight loss pills are thermogenic fat burners that were once popular in the UK, but are no longer widely available or recommended. These pills claimed to boost metabolism and increase fat burning through caffeine and other stimulants. However, modern prescription weight loss medication — including GLP-1 injections like Wegovy (semaglutide) and Mounjaro (tirzepatide) — now offers evidence-based alternatives with clinical trial support. If you're interested in weight management in the UK, your GP can discuss safe, licensed options tailored to your health needs.
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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 T5s Work and Why They're Less Common Today
T5 weight loss pills work by stimulating the central nervous system, primarily through high doses of caffeine combined with ingredients like synephrine (from bitter orange) and other herbal extracts. The theory was that these stimulants would increase heart rate and metabolic rate, leading to greater fat burning — particularly during rest and exercise.
However, T5s became less common in the UK due to safety concerns: they caused jitteriness, anxiety, insomnia, elevated blood pressure, and potential cardiac stress. Modern prescription weight loss medication takes a different approach entirely. Wegovy (semaglutide) and Mounjaro (tirzepatide) are GLP-1 and dual GIP/GLP-1 receptor agonists that work on appetite regulation and glucose control rather than stimulant action. Clinical trials show these prescription options produce significant, sustained weight loss without the side effect profile of stimulant-based pills.
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.
Prescription Weight Loss Options Available in the UK
If you're looking for evidence-based weight loss medication, the NHS and private prescribers now offer licensed alternatives. Wegovy (semaglutide 2.4 mg) is a once-weekly injection that helped participants lose approximately 15% of body weight on average in clinical trials. Mounjaro (tirzepatide) is a dual-action injection offering similar or greater results — approximately 15–21% average weight loss. Both are prescription-only and require clinical assessment by a licensed prescriber.
Access is available through NHS specialist weight management services (tier 3) or private online prescribing following consultation. Your GP can refer you to local services, or you can seek a private clinical assessment. Calculate your BMI and explore whether you might be eligible using our free BMI calculator on this page.
- 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.
Are T5 weight loss pills still available in the UK?
T5 weight loss pills are largely unavailable through legitimate UK pharmacies due to safety concerns and regulatory restrictions. Some unregulated online sources may still sell them, but these carry significant health risks and lack medical oversight. Licensed, prescription-only weight loss medications like Wegovy and Mounjaro are the evidence-based alternatives now recommended in the UK.
What's the difference between T5 pills and modern weight loss injections?
T5 pills use stimulants (caffeine, synephrine) to increase metabolism — a high-risk approach with jitteriness and cardiac side effects. Modern GLP-1 injections (Wegovy, Mounjaro) work on appetite control and glucose regulation with proven clinical efficacy and better safety profiles. GLP-1 medications are prescription-only and require clinical assessment.
How much weight can you lose with prescription weight loss medication?
Clinical trials show GLP-1 medications produce average weight loss of 14–21% of body weight alongside diet and exercise. Individual results vary significantly. The STEP-1 trial (Wegovy) showed approximately 15% average loss; SURMOUNT-1 (Mounjaro) showed 15–21% depending on dose. Always discuss realistic expectations with your prescriber.
How do I access prescription weight loss medication on the NHS?
Ask your GP for a referral to your local tier 3 specialist weight management service. NHS access depends on your BMI, health conditions, and regional availability — waiting times vary. Alternatively, private online prescribers (GPhC-registered) offer faster access following a clinical consultation. Check eligibility with a healthcare professional first.
What should I do if I'm considering weight loss medication?
Start by checking your BMI using our free BMI calculator above. Then speak with your GP about weight management options available to you — including lifestyle support, NHS services, or private prescribing. A healthcare professional can assess whether medication is appropriate for your individual health profile and discuss all suitable alternatives.
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.