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
Weight Loss — NHS-Backed Guidance for UK Adults
Losing weight safely and sustainably is one of the most important steps you can take for your long-term health. In the UK, around 63% of adults are overweight or obese, which significantly increases the risk of type 2 diabetes, heart disease, and other serious health conditions. The good news is that even modest weight loss — as little as 5–10% of your current body weight — can bring real health benefits. This guide covers evidence-based weight loss strategies aligned with NHS recommendations, helping you understand what works and how to approach weight management safely.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
NHS Recommendations for Safe, Sustainable Weight Loss
The NHS recommends losing weight at a rate of 0.5 to 1 kg per week for sustainable, long-term results. This typically requires a calorie deficit of around 500 kcal per day, which can be achieved through a combination of dietary changes and increased physical activity.
- A healthy BMI range is 18.5 to 24.9 according to NHS guidelines (lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults)
- Even a 5% reduction in body weight can improve blood pressure, blood sugar control, and cholesterol levels
- Very low calorie diets (under 800 kcal/day) should only be followed under medical supervision
- Sustainable weight loss combines dietary changes, increased physical activity, and behaviour change
- Your GP can refer you to NHS specialist weight management services (tier 3) if you need additional support
Use our free BMI calculator above to check your personal BMI, and our weight converter to track your progress in stone, pounds, or kilograms — whichever you prefer.
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.
UK Weight Loss Tools and Getting GP Support
If you're overweight or living with obesity, your first step is to speak with your GP, who can assess your individual health and discuss options. The NHS offers free support through tier 1 programmes like the NHS Weight Loss Plan, which uses digital tools and community-based guidance.
For more structured support, your GP can refer you to tier 3 specialist weight management services, where you may be eligible for prescription weight loss medications alongside lifestyle changes. Our GLP-1 weight loss calculator can help you understand potential outcomes with medication support. You can also log and track your weight loss journey using our free progress tracker, which helps you stay motivated and see your progress over time.
- 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.
What is a safe rate of weight loss according to NHS guidance?
The NHS recommends losing 0.5 to 1 kg per week, which is sustainable and reduces muscle loss risk. This typically requires a 500 kcal daily deficit through diet and activity combined. Faster weight loss is possible under medical supervision but isn't recommended long-term without professional support.
How much weight loss brings health benefits?
Even a 5–10% reduction in body weight can significantly improve your health. Benefits include lower blood pressure, better blood sugar control, reduced cholesterol, less joint pain, improved sleep, and lower risk of type 2 diabetes and cardiovascular disease.
What weight loss options are available through the NHS in the UK?
The NHS offers tier 1 self-help programmes (digital tools, community groups), tier 2 primary care interventions, tier 3 specialist weight management services (where prescription medications may be offered), and tier 4 bariatric surgery for severe obesity. Your GP can discuss which is appropriate for you.
Can I use a healthy weight range calculator to set my goal weight?
Yes. Our free BMI calculator shows your healthy weight range based on your height. A BMI of 18.5–24.9 is considered healthy for most adults (lower for some ethnic groups). Your GP can help personalise this based on your individual health and circumstances.
Are prescription weight loss injections available in the UK?
Yes. Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only weight management injections licensed in the UK. They're available through NHS specialist services or private prescribing following clinical assessment. Our GLP-1 weight loss calculator can help you understand how these work alongside diet and activity.
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.