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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Does L Carnitine Help With Weight Loss?
L-carnitine is an amino acid supplement widely promoted for weight loss, but the evidence for its effectiveness in helping adults lose weight remains mixed and limited. If you're looking to manage your weight in the UK, there are more scientifically-supported options available — particularly prescription weight loss medications for eligible adults. This guide explains what the evidence actually shows about L-carnitine and introduces the prescription weight management options available through the NHS and private prescribing.
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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.
What Does the Evidence Say About L-Carnitine?
L-carnitine is produced naturally in your body and plays a role in fat metabolism by transporting fatty acids into cells for energy. However, most clinical trials investigating L-carnitine supplementation for weight loss have shown modest or no significant benefit when compared to placebo. A 2018 systematic review found that while some studies showed small weight reductions, the effect sizes were generally very small and not clinically meaningful.
Most people obtain sufficient L-carnitine through their diet — particularly from meat and dairy products — meaning supplementation is unlikely to provide additional benefit unless there is a documented deficiency. L-carnitine supplements are unregulated as food supplements, unlike prescription weight loss medication which undergoes rigorous clinical testing and MHRA approval. If you're interested in evidence-based weight management, prescription options like Mounjaro and Wegovy are backed by extensive clinical trial data showing average weight loss of 15–21% of body weight in real-world use.
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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.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
UK Prescription Weight Loss Options for Eligible Adults
If you have a BMI of 30 or above, or 27 or above with weight-related health conditions, you may be eligible for prescription weight loss medication in the UK. Licensed options include Mounjaro (tirzepatide), a once-weekly injection combining GIP and GLP-1 activity, and Wegovy (semaglutide), a once-weekly GLP-1 injection. Both have been extensively studied and approved by the MHRA for weight management. Access is available through NHS specialist weight management services or via private prescribing following an online clinical assessment. Check your BMI using our free BMI calculator, then speak with your GP about eligibility and which approach suits your situation best.
- 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 L-carnitine worth taking for weight loss?
Clinical evidence suggests L-carnitine supplementation produces only minimal weight loss, if any. Most healthy adults get sufficient L-carnitine from their diet. If weight loss is your goal, discuss evidence-based options with your GP — particularly prescription medication if you meet eligibility criteria.
What is the difference between L-carnitine and prescription weight loss medication?
L-carnitine is an unregulated food supplement with limited evidence of effectiveness. Prescription medications like Mounjaro and Wegovy undergo rigorous MHRA testing and clinical trials, with proven average weight loss of 15–21%. They require a prescription and clinical assessment to ensure suitability.
Who is eligible for prescription weight loss medication in the UK?
Adults with a BMI of 30 or above, or 27 or above with weight-related health conditions (such as type 2 diabetes, high blood pressure, or cardiovascular disease), may be eligible. Ethnicity-adjusted thresholds apply for South Asian and Black African backgrounds. Your GP can assess your eligibility.
How can I find out if prescription weight loss treatment is right for me?
Book an appointment with your GP to discuss weight management options. They can assess your BMI, health history, and eligibility for prescription treatment. You can calculate your BMI in advance using our free BMI calculator to bring to the appointment.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist with average weight loss of 15–21%. Wegovy (semaglutide) is a GLP-1 agonist only with average weight loss around 15%. Both are once-weekly injections. Your prescriber will recommend the option most suited to your individual health profile.
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.