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
Complex Carbs for Weight Loss: A UK Guide
Complex carbohydrates are an important part of a balanced, sustainable weight loss diet. Unlike simple sugars, complex carbs release energy slowly, helping you feel fuller for longer and avoid energy crashes. This guide explains which foods to choose and how they fit into a UK weight management strategy—including prescription options available through the NHS and private prescribers for eligible adults.
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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.
Which Complex Carbs Support Weight Loss?
Complex carbohydrates contain more fibre and nutrients than refined carbs, making them ideal for weight loss. Key examples include:
- Whole grains: oats, brown rice, wholemeal bread, quinoa, barley
- Pulses and legumes: lentils, chickpeas, beans (black, kidney, cannellini)
- Starchy vegetables: sweet potatoes, parsnips, corn
- Fruits: berries, apples, bananas, oranges (with skin intact)
These foods are high in fibre, which slows digestion and keeps you satisfied longer. Fibre also supports blood sugar stability—important for preventing cravings and energy slumps. Aim to fill roughly one quarter of your plate with complex carbs at each meal, alongside protein and vegetables. When combined with reduced overall calories (typically a 500 kcal daily deficit for sustainable loss of about 0.5 kg per week), complex carbs provide steady energy without sabotaging your progress.
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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 Management Options in the UK
If diet and exercise alone aren't delivering results, prescription weight loss medication is available in the UK for eligible adults. The NHS offers referral to tier 3 specialist weight management services, where medications like tirzepatide (Mounjaro) and semaglutide (Wegovy) may be prescribed. Private online prescribers also offer these options following a clinical assessment. Eligibility typically requires a BMI of 30 kg/m² or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes or high blood pressure. These medications work by reducing appetite and food cravings, making it easier to maintain a calorie deficit alongside a healthy diet of complex carbs. Check your BMI instantly with our free BMI calculator above, and speak to your GP about whether prescription weight management is right for you.
- 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.
Are complex carbs allowed on weight loss diets?
Yes. Complex carbs are essential for sustainable weight loss. They're higher in fibre than refined carbs, keeping you fuller longer and providing steady energy. The key is portion control—fill one quarter of your plate with complex carbs, balance with protein and vegetables, and maintain a calorie deficit of approximately 500 kcal per day for gradual, healthy loss.
What's the difference between complex and simple carbs?
Simple carbs (white bread, sugary foods, refined grains) are digested quickly, causing blood sugar spikes and energy crashes. Complex carbs (oats, lentils, sweet potatoes, brown rice) contain more fibre and nutrients, digesting slowly and keeping you satisfied longer. This makes complex carbs better for weight loss and overall health.
Can I use our GLP-1 weight loss calculator to estimate results with medication?
Yes. Our free GLP-1 weight loss calculator lets you estimate potential weight loss at different doses of medications like Mounjaro and Wegovy. Remember that real-world results vary based on individual factors, diet adherence, and exercise. Always combine prescription medication with a balanced diet including complex carbs for best results.
How do I access prescription weight loss medication through the NHS?
Ask your GP for a referral to your local tier 3 specialist weight management service. Availability and waiting times vary by region. Alternatively, private online prescribers offer assessment and prescription following an online consultation. Your GP can advise which route suits your circumstances.
What BMI qualifies me for prescription weight loss treatment?
You may be eligible with a BMI of 30 kg/m² or above, or 27–29.9 with weight-related health conditions (type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease). Use our free BMI calculator to check your current BMI, then discuss eligibility with your GP or a licensed prescriber.
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.