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
Can Porridge Help With Weight Loss?
Porridge can be part of a healthy weight loss plan, especially when portion-controlled and made with water or unsweetened milk. However, breakfast choices alone won't create sustained weight loss — you need a consistent calorie deficit across the whole day. For adults in the UK who are overweight or obese, prescription weight management options like Mounjaro and Wegovy are available alongside lifestyle changes. Our free BMI calculator above can help you check your current weight status and understand what a healthy weight range looks like for your height.
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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.
Prescription Weight Loss Options Available in the UK
If you've tried dietary changes like porridge-based breakfasts without seeing results, prescription weight management medications are available in the UK for eligible adults. Three main options are licensed:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 injection given once weekly, with average weight loss of 15–21% in clinical trials
- Wegovy (semaglutide) — a GLP-1 injection given once weekly, with average weight loss of around 15% in clinical trials
- Saxenda (liraglutide) — a GLP-1 injection given daily, offering similar results to Wegovy
These are prescription-only medicines that require a clinical assessment. You're eligible if you have 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. Our GLP-1 weight loss calculator can help you explore potential outcomes at different medication 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.
NHS vs Private Access — How to Get Started
In the UK, you can access prescription weight loss medication through two routes:
- NHS: Referral through your GP to a specialist tier 3 weight management service. Availability and waiting times vary significantly by region
- Private: Online consultation with a UK-licensed prescriber, assessment, and prescription through a GPhC-registered pharmacy — available without NHS referral
Either way, a prescriber will assess whether medication is suitable for you based on your health history. Speak to your GP first about your weight loss goals. If NHS access is limited in your area, they can advise you on private options. Prescription medications work best alongside dietary changes (like your porridge breakfasts) and increased physical activity, not instead of them.
- 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 porridge a good breakfast for weight loss?
Porridge can support weight loss when made with water or unsweetened milk and kept to a reasonable portion (around 40g of oats). It's filling due to fibre content, which may help reduce snacking later. However, weight loss ultimately depends on total daily calorie intake, not breakfast choice alone. Use our free progress tracker to monitor your overall results.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections. Mounjaro uses a dual mechanism (GIP and GLP-1), whilst Wegovy uses GLP-1 only. Clinical trials show Mounjaro achieves slightly higher average weight loss (15–21% vs 15%), but individual results vary. A prescriber will recommend the most suitable option for you.
Who is eligible for prescription weight loss medication in the UK?
Adults with a BMI of 30 or above are eligible. Those with a BMI of 27–29.9 may also qualify if they have weight-related health conditions like type 2 diabetes, high blood pressure, or cardiovascular disease. Check your BMI using our free calculator above, then speak to your GP.
Can I get weight loss injections on the NHS?
Yes, but access is through specialist tier 3 weight management services via GP referral. Availability varies by region and waiting lists can be lengthy. If NHS access is limited, private prescribing is available through registered pharmacies following an online consultation with a UK-licensed prescriber.
How quickly will prescription weight loss medication work?
Results vary between individuals. Most people see modest weight loss within the first 4–8 weeks, with continued loss over months. These medications work best alongside calorie reduction and exercise. Combine medication with dietary changes like portion-controlled porridge breakfasts for best results.
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.