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
Magnesium Citrate and Weight Loss — What You Need to Know
Magnesium citrate is a supplement often discussed in weight loss contexts, but it's not a weight loss medication. While magnesium plays a role in metabolism and muscle function, magnesium citrate is primarily used as a laxative for constipation relief. If you're looking to lose weight in the UK, prescription weight management options like Mounjaro and Wegovy have robust clinical evidence and NHS approval. This guide explains what magnesium citrate actually does and which evidence-based options are genuinely available for weight management in the UK.
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're interested in weight management in the UK, prescription weight loss medication is available through the NHS and private prescribers for eligible adults. The main options are:
- Mounjaro (tirzepatide) — a once-weekly injection that activates dual GIP and GLP-1 pathways. Clinical trials showed an average weight loss of 15–21% of body weight over 72 weeks when combined with a reduced-calorie diet and increased physical activity.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection with clinical evidence showing approximately 15% average weight loss at the highest dose.
- Saxenda (liraglutide) — a daily GLP-1 injection, typically producing modest weight loss outcomes.
All three are prescription-only and require a clinical assessment to confirm eligibility. They work by affecting hormones that regulate appetite and fullness, quite differently from how supplements work. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses.
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.
Who Is Eligible and How to Start
In the UK, you may be eligible for prescription weight loss treatment if you have a BMI of 30 or above, or a BMI of 27–29.9 with at least one weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea. South Asian, Chinese, Black African, and Black Caribbean adults have lower BMI eligibility thresholds due to higher cardiovascular risk at lower weights.
Access routes differ: NHS weight loss typically requires referral to a tier 3 specialist weight management service through your GP, though waiting lists vary by region. Private prescription weight loss is available through online consultations with UK-licensed prescribers, without NHS referral. Check your BMI using our free BMI calculator to see where you stand, then speak with your GP about your options.
- 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 magnesium citrate actually help you lose weight?
Magnesium citrate is not a weight loss supplement. It's primarily a laxative used for constipation relief. While magnesium is essential for metabolism and muscle function, taking magnesium citrate won't create the calorie deficit needed for weight loss. If you're looking for evidence-based weight loss support, prescription medications like Mounjaro and Wegovy are far more effective.
What's the difference between supplements and prescription weight loss medication?
Supplements like magnesium citrate are not clinically proven for weight loss. Prescription weight loss medications like Mounjaro and Wegovy have undergone rigorous clinical trials and are licensed for weight management in the UK. They work on specific appetite-regulating hormones and produce measurable, significant weight loss when combined with lifestyle changes.
How do I know if I'm eligible for prescription weight loss treatment in the UK?
You may be eligible if your BMI is 30 or above, or 27–29.9 with a weight-related health condition like diabetes or high blood pressure. Ethnicity-adjusted thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults. Use the BMI calculator on this page, then speak with your GP about referral to specialist weight management services or private prescribing options.
What's the difference between NHS and private weight loss medication in the UK?
NHS weight loss medication is accessed through tier 3 specialist weight management services after GP referral, though availability and waiting times vary by region. Private prescription weight loss is available online from UK-licensed prescribers without NHS referral, typically faster but at personal cost. Both require a clinical assessment to confirm eligibility and suitability.
How much weight can I expect to lose with prescription weight loss medication?
Clinical trials show that Mounjaro helps participants lose an average of 15–21% of body weight, while Wegovy produces approximately 15% average weight loss. Individual results vary significantly and depend on dose, adherence, diet, and physical activity. These medications work alongside a reduced-calorie diet and exercise, not instead of them. Our weight loss calculator can show you potential projections.
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.