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 Diet for Weight Loss in the UK
Finding the best diet for weight loss depends on what you can sustain long-term, rather than following restrictive short-term approaches. The NHS recommends losing weight at a rate of 0.5 to 1 kg per week through a combination of dietary changes and increased physical activity. Various evidence-based diets have shown results in weight management UK research, from calorie deficit approaches to Mediterranean-style eating patterns. Success depends on your individual circumstances, preferences, and any underlying health conditions. Your GP can provide personalised advice about which approach suits you best.
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 Dietary Approaches That Work
Several dietary approaches have strong evidence for sustainable weight loss. A calorie deficit of around 500 kcal per day typically results in approximately 0.5 kg per week loss, making it a reliable foundation for nhs weight loss planning. The Mediterranean diet combines weight loss with cardiovascular health benefits and is widely recommended by UK healthcare professionals. Intermittent fasting approaches (such as 16:8 or 5:2) can help reduce overall calorie intake, though individual results vary.
- Low-carbohydrate diets show rapid initial weight loss, though long-term outcomes are similar to calorie restriction
- Balanced, protein-rich approaches support muscle preservation during weight loss
- Whole foods and minimally processed foods help with satiety and nutrient intake
- Regular meal timing reduces impulsive eating and supports consistency
Use our free BMI calculator above to track where you currently stand, and remember that sustainable change is more valuable than gradual weight management.
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.
When Diet Alone Isn't Enough: Support and Treatment Options
If you've tried dietary changes and lifestyle adjustments without sufficient success, prescription weight loss medication may be an option. GLP-1 weight loss injections (such as Wegovy or Mounjaro) are licensed in the UK and may help alongside continued diet and exercise. These work by supporting appetite regulation and are available through NHS specialist services or private prescription following a clinical assessment.
Our GLP-1 weight loss calculator can help you explore potential outcomes with different approaches. Whether pursuing diet-only weight management uk or considering medication support, your GP is the best starting point for personalised guidance based on your health profile and BMI.
- 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 best diet for sustainable weight loss?
The best diet is one you can maintain long-term. Evidence supports calorie deficit approaches (around 500 kcal/day for 0.5 kg/week loss), Mediterranean-style eating, and approaches emphasising whole foods. The NHS recommends combining dietary changes with increased physical activity for optimal results.
How quickly should I lose weight?
The NHS recommends losing weight at 0.5 to 1 kg per week as a safe, sustainable rate. Faster weight loss increases risks of muscle loss, nutritional deficiencies, and weight regain. Consistency over months and years matters more than rapid initial loss.
Should I try a very low calorie diet?
Very low calorie diets (under 800 kcal/day) should only be followed under medical supervision and are not recommended for self-directed weight loss. Standard calorie deficit approaches are safer and more sustainable for most people.
Can prescription weight loss medication help if diet isn't working?
Yes. If you have a BMI of 30 or above, or 27 or above with weight-related health conditions, you may be eligible for prescription weight loss treatment. These medications work alongside diet and exercise, not instead of them. Your GP can assess whether this is appropriate.
How do I know which weight loss approach is right for me?
Your GP is the best person to advise based on your individual health, medical history, and preferences. Try our free BMI calculator to understand your starting point, then discuss personalised options with your healthcare provider for the most effective, sustainable approach.
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.