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
Does Magnesium Help With Weight Loss?
Magnesium is a mineral involved in hundreds of bodily processes, including metabolism and blood sugar regulation. Many people wonder if taking magnesium supplements can support weight loss. The short answer is: magnesium may play a supporting role in weight management, but it's not a weight loss solution on its own. Evidence suggests it may help indirectly by improving insulin sensitivity and reducing cravings, particularly if you're deficient. However, sustainable weight loss in the UK requires calorie reduction and physical activity — supplements alone don't produce results.
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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.
How Magnesium May Support Weight Management
Magnesium affects weight management through several mechanisms. First, it plays a role in glucose and insulin metabolism — adequate magnesium helps your body regulate blood sugar more effectively, which can reduce cravings and energy crashes. Second, magnesium is involved in muscle function and energy production, meaning deficiency can make exercise feel harder and recovery slower.
Third, magnesium may help reduce inflammation and improve sleep quality — both factors linked to weight gain. Poor sleep disrupts hormones that regulate appetite (ghrelin and leptin), while chronic inflammation is associated with weight gain and metabolic dysfunction. If you're deficient in magnesium, supplementation may improve these factors. However, it's important to note: magnesium supplementation is not a substitute for the calorie deficit needed for weight loss. The NHS recommends losing weight at a sustainable rate of 0.5 to 1 kg per week, which requires both dietary changes and increased physical activity.
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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.
Magnesium Deficiency and Weight — What the Evidence Shows
Research suggests that people with magnesium deficiency may struggle more with weight management than those with adequate magnesium. Studies link low magnesium to insulin resistance, type 2 diabetes risk, and metabolic syndrome — all barriers to effective weight loss. If blood tests show you're deficient, your GP may recommend supplementation.
However, if you already have adequate magnesium intake through food — nuts, seeds, leafy greens, whole grains — additional supplements won't accelerate weight loss. More isn't better. A balanced approach combines magnesium-rich foods, adequate physical activity, and a sustainable calorie deficit. Use our free BMI calculator and weight converter to understand your current weight context, then speak to your GP about a personalised weight management plan that may include dietary changes, exercise, and if appropriate, prescription weight loss medication alongside lifestyle changes.
- 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.
Can magnesium supplements alone help me lose weight?
No. Magnesium may support weight management indirectly by improving insulin sensitivity, sleep, and muscle function — but it's not a weight loss tool on its own. Weight loss requires a calorie deficit achieved through diet and exercise. If you're deficient, supplementation may help you feel better and exercise more effectively, but it won't cause weight loss without lifestyle changes.
How much magnesium should I take for weight loss?
There's no "weight loss dose" of magnesium. The recommended daily intake is 300–400 mg for most UK adults. Excess magnesium is excreted in urine, so taking more doesn't improve results. Speak to your GP or a registered dietitian before starting supplements — they can check if you're deficient and recommend an appropriate dose.
Does magnesium help reduce appetite or cravings?
Possibly, indirectly. Magnesium deficiency is linked to increased sugar cravings and poor blood sugar control. If you're deficient, adequate magnesium may help stabilise energy and reduce cravings. However, the primary way to manage cravings is through a balanced diet with adequate protein, fibre, and whole foods — plus addressing sleep and stress.
Is magnesium supplementation safe for long-term use?
Yes, for most people. High-quality magnesium supplements at the recommended dose are generally safe. However, very high doses can cause diarrhoea, nausea, and medication interactions. Always inform your GP or pharmacist about supplements you're taking, especially if you're on prescription medications or have kidney problems.
Should I use magnesium instead of prescription weight loss medication?
No. Magnesium is a dietary supplement; prescription weight loss medications like Mounjaro and Wegovy work through completely different mechanisms (GLP-1 and GIP receptor activation). Magnesium supports general health and may aid weight management indirectly. If you meet NHS criteria for prescription weight loss medication, your GP can assess whether it's appropriate for you — this requires a clinical assessment, not a supplement decision.
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.