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
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Free Diet Plan for Weight Loss in the UK
A free diet plan for weight loss doesn't have to mean expensive programmes or restrictive eating. In the UK, you have access to evidence-based approaches through the NHS, plus prescription weight management options if you're eligible. This guide covers practical dietary strategies, how to calculate your personal calorie needs using your BMI, and the prescription medications available for weight loss. Whether you're looking to lose weight sustainably or exploring all available options, understanding what's free and what requires a prescription helps you make the right choice for your health.
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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 Weight Loss Options: Free and Prescription Routes
Free approaches include the NHS Weight Loss Plan (a 12-week digital programme), self-guided calorie reduction (typically 500 kcal/day deficit for ~0.5 kg/week loss), and increased physical activity. The NHS recommends sustainable weight loss of 0.5–1 kg per week.
For eligible adults, prescription weight loss medication is also available in the UK:
- Mounjaro (tirzepatide) — dual GIP/GLP-1 injection, up to 15 mg weekly; clinical trials showed average weight loss of 15–21% body weight
- Wegovy (semaglutide) — GLP-1 injection, up to 2.4 mg weekly; average weight loss around 15% body weight in trials
- Saxenda (liraglutide) — GLP-1 daily injection
These are prescription-only and require a clinical assessment. Calculate your BMI using our free calculator above to understand your starting point for weight management, then discuss options with your GP.
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 Access vs Private: How to Get Started
The NHS provides free weight management support through tier 1 and tier 2 services (self-help, community programmes, and GP-led support). Prescription medications like Mounjaro and Wegovy are available through NHS specialist tier 3 services, though availability and waiting times vary significantly by region.
Private prescription options are also available through UK-licensed online prescribers following a clinical assessment — typically faster but at a cost.
Start by speaking to your GP about your weight loss goals. They can assess whether you're eligible for prescription weight management, refer you to specialist services if appropriate, or signpost you to free local programmes. Our free GLP-1 weight loss calculator can help you explore potential outcomes if you become eligible for prescription medication.
- 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 I get a free diet plan on the NHS?
Yes. The NHS Weight Loss Plan is a free 12-week digital programme available to adults in England with a BMI over 25. Your GP can refer you, or you can self-refer via the NHS website. It provides support, meal ideas, and activity guidance. Many local authorities also offer free community weight management programmes.
What's the difference between a free diet plan and prescription weight loss medication?
A free diet plan relies on calorie reduction and lifestyle change. Prescription medications like Mounjaro and Wegovy work alongside diet and exercise to reduce appetite and support weight loss. Medications are prescribed based on your BMI and health conditions — they're not available to everyone and require clinical assessment.
How much weight can I lose with a free diet plan?
The NHS recommends losing 0.5–1 kg per week, which is sustainable and safe. This typically requires a calorie deficit of around 500 kcal/day. Individual results depend on your starting weight, adherence, and metabolism. Use our BMI calculator to set realistic goals for your height and current weight.
Am I eligible for prescription weight loss medication on the NHS?
Eligibility depends on your BMI and health conditions. Generally, adults with a BMI of 30 or above, or 27–29.9 with weight-related conditions (like type 2 diabetes or high blood pressure), may qualify. Some ethnic groups have lower thresholds. Speak to your GP for a personalised assessment.
How do I start a free weight loss journey in the UK?
Begin by using our free BMI calculator to understand your current health weight category. Then speak to your GP about free NHS support (Weight Loss Plan, local programmes) or specialist services if eligible. Track your progress with our free progress tracker to stay motivated throughout your weight management journey.
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.