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
Cod Liver Oil and Weight Loss — What UK Adults Should Know
Cod liver oil is a popular supplement rich in omega-3 fatty acids and vitamin D, often promoted for various health benefits. However, if you're looking for effective weight management in the UK, prescription weight loss medications offer stronger clinical evidence. This guide explains what cod liver oil can and cannot do for weight loss, and introduces the prescription options available to eligible UK adults through NHS weight management services or private prescribing.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
UK-Licensed Prescription Weight Loss Options
If you have a BMI of 30 or above, or 25–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure, you may be eligible for prescription weight loss medication in the UK. Three main options are currently licensed:
- Mounjaro (tirzepatide) — a once-weekly injection that works as a dual GLP-1 and GIP receptor agonist. Clinical trials showed average weight loss of approximately 15–21% of body weight over 72 weeks, alongside reduced-calorie diet and increased physical activity.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection with average weight loss around 15% in clinical trials.
- Saxenda (liraglutide) — a daily GLP-1 injection, with average weight loss of approximately 5–8% of body weight.
These medications work by reducing appetite and helping you feel fuller after smaller meals. Individual results vary significantly. Use our free GLP-1 weight loss calculator above to explore potential outcomes at different doses. Your GP can assess eligibility and refer you to NHS weight management services, or you can access private prescribing through a UK-licensed prescriber following an online consultation.
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 vs Private Access — How to Find Out If You're Eligible
Access to prescription weight loss treatment in the UK depends on your BMI and health profile. Check your BMI using our free BMI calculator on this page — this is your starting point. Adults with a BMI of 30 or higher, or 27.5–29.9 with weight-related conditions, may be eligible.
NHS route: Ask your GP for a referral to your local tier 3 specialist weight management service. NHS availability and waiting times vary by region (integrated care board). Some areas have several months' waiting lists.
Private route: Online consultations with UK-licensed prescribers assess eligibility and issue prescriptions if appropriate. This is faster than NHS but involves private costs (typically £129–£320 per month depending on dose).
Whichever route you choose, a qualified healthcare professional will review your individual health profile before any medication is prescribed.
- 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 cod liver oil help with weight loss?
Cod liver oil is a nutritious supplement containing omega-3s and vitamin D, which support cardiovascular and bone health. However, it has not been proven to cause significant weight loss. If weight management is your goal, prescription medications like Mounjaro and Wegovy have stronger clinical evidence for weight loss alongside lifestyle changes.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections licensed for UK weight management, but they work differently. Mounjaro is a dual GIP and GLP-1 agonist with average weight loss around 15–21% in trials. Wegovy is a single GLP-1 agonist with average weight loss around 15%. Individual results vary. A prescriber will recommend the most suitable option for your health profile.
How do I know if I'm eligible for prescription weight loss medication in the UK?
You're potentially eligible if your BMI is 30 or above, or 27.5–29.9 with weight-related health conditions (type 2 diabetes, high blood pressure, sleep apnoea, heart disease history). Use our free BMI calculator on this page to check your BMI, then speak with your GP or arrange a private consultation with a UK-licensed prescriber.
Can I get prescription weight loss medication on the NHS?
Yes, if eligible and referred to a specialist tier 3 weight management service. However, availability and waiting times vary significantly by region. Your GP can provide a referral. Alternatively, private online prescribing offers faster access but involves costs of approximately £129–£320 per month depending on dose.
What happens after starting weight loss medication?
Treatment typically involves starting at a low dose and increasing gradually over several weeks to find your optimal dose. You'll be monitored for side effects and weight progress. Weight loss medications work best alongside a reduced-calorie diet and increased physical activity. Track your progress using our free progress tracker on this site. Most people are on medication for at least 12 months; some continue longer.
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.