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
Potatoes for Weight Loss — What Works in the UK
Potatoes often get unfairly blamed for weight gain, but they can actually support healthy eating when prepared simply. However, if you're looking for more structured weight management in the UK, prescription options are available for eligible adults. This guide explains how potatoes fit into a balanced diet, and introduces the prescription weight loss medications now approved by the NHS for weight management.
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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.
UK Prescription Weight Loss Options
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, you may be eligible for prescription weight loss medication in the UK.
Three GLP-1 medications are currently licensed for weight management:
- Mounjaro (tirzepatide) — dual GIP and GLP-1 receptor agonist, once-weekly injection. Clinical trials showed average weight loss of 15–21% of body weight alongside diet and exercise.
- Wegovy (semaglutide) — GLP-1 receptor agonist, once-weekly injection. Clinical trials showed average weight loss of approximately 15% of body weight.
- Saxenda (liraglutide) — GLP-1 receptor agonist, once-daily injection.
All three are prescription-only medicines and require a clinical assessment to determine suitability. Our free GLP-1 weight loss calculator can help you understand 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.
Getting Started — NHS vs Private Access
NHS access: Referral to your GP, who can refer you to a specialist tier 3 or tier 4 weight management service. Availability and waiting times vary significantly by region — some areas have lengthy waiting lists.
Private access: Online consultation with a UK-licensed prescriber, prescription issued if clinically appropriate, then dispensed by a GPhC-registered pharmacy.
Either way, a healthcare professional will assess your BMI, medical history, and eligibility. Use our free BMI calculator above to check where you stand, then have a conversation with your GP about what's right for you. Individual results vary, and medication works best alongside lifestyle changes including balanced nutrition and physical activity.
- 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 potatoes help with weight loss?
Plain boiled or baked potatoes are actually quite filling and can fit into a healthy weight loss diet. The issue is typically preparation — chips, crisps, and heavily buttered potatoes are high in calories. Potatoes are nutritious when prepared simply and eaten in reasonable portions alongside other whole foods and regular physical activity.
Who is eligible for prescription weight loss medication in the UK?
Adults with a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea, may be eligible. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply. Your GP can assess your individual eligibility.
How much weight can I expect to lose with Mounjaro or Wegovy?
Clinical trials showed average weight loss of 15–21% of body weight with Mounjaro and approximately 15% with Wegovy over the trial period. However, individual results vary significantly. These medications work best alongside a reduced-calorie diet and increased physical activity — they are not a substitute for lifestyle changes.
What's the difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 receptor agonist (once-weekly injection), whilst Wegovy is a GLP-1 agonist only (also once-weekly). Both are prescription-only. Mounjaro showed slightly higher average weight loss in clinical trials, but individual results vary. Your prescriber will assess which is more suitable for you.
How do I find out if I'm eligible for weight loss medication on the NHS?
Start by speaking with your GP. They can calculate your BMI, review your health history, and discuss whether referral to a specialist weight management service is appropriate for you. Use our free BMI calculator on this page to check your current BMI, then bring this information to your GP appointment.
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.