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 Ways to Lose Weight in the UK
Losing weight sustainably involves a combination of approaches tailored to your individual circumstances. The NHS recommends a multi-faceted strategy that combines dietary changes, increased physical activity, and behavioural support—with prescription weight loss medication available as an option for eligible adults. Whether you're just starting your weight management journey or looking to understand your options, there are proven methods that work. Our free BMI calculator can help you understand where you stand health-wise, while our weight loss projection calculator lets you explore potential outcomes with different approaches.
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.
Evidence-Based Weight Loss Methods That Work
Calorie deficit through diet: The most fundamental principle of weight loss is consuming fewer calories than you burn. The NHS recommends a deficit of around 500 kcal per day, which typically results in losing approximately 0.5 to 1 kg per week—a sustainable rate that minimises muscle loss. This can be achieved through portion control, choosing lower-calorie foods, and reducing sugary drinks and processed items.
- Mediterranean diet: Strong evidence supports this approach for both weight loss and cardiovascular health, focusing on whole grains, vegetables, lean proteins, and healthy fats.
- Intermittent fasting: Approaches like 16:8 (fasting 16 hours, eating within an 8-hour window) or 5:2 (eating normally 5 days, restricting to 500–600 kcal on 2 days) can support weight loss for some people.
- Low-carbohydrate diets: Effective for short-term weight loss, though long-term outcomes are similar to standard calorie restriction.
Physical activity: Combining aerobic exercise (walking, swimming, cycling) with resistance training preserves muscle mass during weight loss and improves overall health outcomes.
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.
Prescription Weight Loss Options and GLP-1 Medications
For adults with a BMI of 30 or above—or 27 or above with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea—prescription weight loss medications may be available. GLP-1 receptor agonist injections such as Wegovy (semaglutide) and dual GIP/GLP-1 medications like Mounjaro (tirzepatide) are licensed in the UK for weight management. These prescription medicines may help reduce appetite and support feeling fuller after smaller meals. Clinical trials showed average weight loss of 15–21% of body weight—though individual results vary significantly. Our GLP-1 weight loss calculator can help you explore potential outcomes at different doses. Always discuss eligibility with your GP or a licensed prescriber, as these medications require a clinical assessment and are used alongside dietary changes and increased 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.
What is the safest rate of weight loss?
The NHS recommends losing 0.5 to 1 kg (1 to 2 lbs) per week as a safe, sustainable rate. This pace minimises muscle loss and helps establish long-term healthy habits. Faster weight loss is possible with medical supervision but increases the risk of nutrient deficiency and muscle loss.
How can I calculate my healthy weight range?
Use your height to calculate a healthy BMI range of 18.5 to 24.9. You can instantly calculate your personal healthy weight range using our free BMI calculator on this page. For adults of South Asian or Black African heritage, the NHS recommends lower thresholds (18.5 to 22.9).
Are weight loss injections available on the NHS?
Prescription weight loss medications like Mounjaro and Wegovy are available through NHS specialist weight management services (tier 3/4), though availability varies significantly by region and waiting lists can be lengthy. Private prescribing is also available through online clinical assessments with UK-licensed prescribers.
What is the difference between Wegovy and Ozempic?
Both contain semaglutide, but Ozempic (up to 2 mg) is approved for type 2 diabetes management, while Wegovy (up to 2.4 mg) is specifically licensed for weight management in the UK. Ozempic is not licensed for weight loss—using it for this purpose is off-label.
How much weight can I expect to lose with medication?
Clinical trial data shows average weight loss of 15–21% of body weight with prescription GLP-1 medications over 68 weeks—but individual results vary considerably. Weight loss depends on dose, adherence to medication, dietary changes, physical activity, and personal metabolism. Your prescriber can discuss realistic expectations during assessment.
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.