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
Best Meal Supplement for Weight Loss in the UK
When searching for the best meal supplement for weight loss, it's important to understand what actually works and what the evidence shows. In the UK, meal replacements and weight management supplements can play a supporting role, but prescription weight loss medications and lifestyle changes remain the most effective approaches. This guide covers the options available, how they work, and what the NHS recommends for sustainable weight loss.
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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.
Meal Supplements vs Prescription Weight Loss Options
Meal replacement supplements—such as shakes, bars, and powders—can help create a calorie deficit by replacing higher-calorie meals with portion-controlled alternatives. However, evidence shows that prescription weight loss injections often produce stronger results than meal supplements alone.
- Meal replacements: Typically provide 200–400 kcal per serving; helpful for structure and portion control, but require sustained lifestyle commitment
- GLP-1 injections (Wegovy, Mounjaro): Prescription-only medications that work by reducing appetite and supporting feeling fuller; clinical trials showed average weight loss of 14–21% of body weight when combined with diet and exercise
- Combination approach: Many people benefit from using meal supplements alongside prescribed weight loss medication under GP or prescriber guidance
The NHS recommends a calorie deficit of approximately 500 kcal per day for sustainable weight loss of 0.5–1 kg per week. Your GP can advise whether prescription weight loss medication is appropriate for your individual health profile.
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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.
Choosing the Right Weight Management Approach for You
If you're considering meal supplements for weight management in the UK, evaluate whether you need additional support. Meal replacements work best when combined with behaviour change and physical activity. For more significant weight loss, especially if you have a BMI of 30 or above or a BMI of 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure, prescription weight loss medication may be worth discussing with your GP.
Use our free BMI calculator to check your current BMI and understand whether you might be eligible for prescription weight loss treatment. Our GLP-1 weight loss calculator can also help you estimate potential results with prescription options, allowing you to make an informed decision about the right approach for your circumstances.
- 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 meal replacement shakes effective for weight loss?
Meal replacements can be helpful as part of a weight loss plan because they control calories and portion sizes. However, evidence shows they work best when combined with behaviour change and increased physical activity. Individual results vary, and sustainable weight loss typically requires dietary changes and lifestyle support. For NHS weight loss guidance, consult your GP.
What's the difference between meal supplements and prescription weight loss medication?
Meal supplements reduce calories through portion control, while prescription medications like Wegovy (semaglutide) and Mounjaro (tirzepatide) work by reducing appetite and helping you feel fuller. Clinical trials showed prescription options produce average weight loss of 14–21% of body weight, often more than meal supplements alone. Both require commitment to lifestyle changes.
Can I use meal supplements alongside weight loss injections?
Yes—many people combine meal replacements with prescription weight loss medication. However, always inform your prescriber about any supplements you're using. GLP-1 injections may slow stomach emptying, which can affect how your body processes other foods and supplements. Your prescriber can advise what's safe to combine.
How do I know if I'm eligible for prescription weight loss medication in the UK?
Adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions, may be eligible. Prescription weight loss medication requires a clinical assessment from your GP or a licensed prescriber. Lower BMI thresholds may apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage due to higher health risks at lower weights.
What's the safest rate of weight loss according to the NHS?
The NHS recommends losing 0.5–1 kg (1–2 lbs) per week for sustainable, healthy weight loss. This typically requires a calorie deficit of about 500 kcal per day. Faster weight loss is possible with medical support but increases the risk of muscle loss and nutritional deficiencies. Always consult your GP before starting any weight loss plan.
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.