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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What are the best macros for weight loss?
Finding the right macro balance is one of the most effective approaches to sustainable weight loss in the UK. Macronutrients — protein, carbohydrates, and fats — are the three main nutrients your body needs for energy and function. The proportion of each macro you consume can significantly impact how effectively you lose weight, how you feel during the process, and whether you can maintain your results long-term. While there's no single "perfect" macro ratio that works for everyone, evidence-based guidance can help you find the right balance for your individual needs and lifestyle.
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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.
The three key macronutrients explained
Protein is considered the most important macro for weight loss. It has the highest thermic effect of food, meaning your body burns more calories digesting it compared to carbs or fat. Protein also helps preserve muscle mass during weight loss and keeps you feeling fuller for longer, which naturally reduces overeating. Most weight loss guidelines recommend 1.6–2.2g of protein per kg of body weight daily. Good UK protein sources include chicken, fish, Greek yoghurt, eggs, beans, and lentils.
Carbohydrates are not "bad" — your body needs them for energy. The key is choosing quality sources: whole grains, vegetables, oats, and legumes rather than refined carbs like white bread and sugary foods. Complex carbs digest slowly, keeping you stable and satisfied. Most evidence-based weight loss plans allocate 40–50% of daily calories to carbs.
Fat is essential for hormone production and nutrient absorption. Healthy fats from avocados, nuts, olive oil, and fatty fish support weight loss by promoting satiety. Aim for 20–35% of daily calories from fat, prioritising unsaturated fats over saturated ones.
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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.
Macro ratios that support sustainable weight loss
There's no single "best" macro ratio — it depends on your preferences, lifestyle, and health conditions. However, three evidence-based approaches work well for UK weight loss:
- Balanced approach: 30% protein, 40% carbs, 30% fat — ideal for most people and supports long-term adherence
- Higher protein approach: 35% protein, 35% carbs, 30% fat — particularly effective if you exercise regularly or want to preserve muscle
- Moderate low-carb approach: 30% protein, 30% carbs, 40% fat — some people find this more satisfying and easier to sustain
The most important factor is maintaining a calorie deficit. The NHS recommends a deficit of around 500 kcal per day for gradual, sustainable loss of approximately 0.5–1 kg per week. Use our free BMI calculator to establish your current position, and our weight loss calculator can help you understand realistic targets alongside your calorie and macro plan.
- 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.
Does macro ratio matter more than total calories for weight loss?
Total calories remain the foundation — you cannot lose weight without a calorie deficit. However, macro ratio affects how you feel during that deficit. Higher protein intake reduces hunger and muscle loss, whilst balanced carbs and fat support energy and hormonal health. Both matter, but calories come first.
What's the best macro ratio for someone taking weight loss medication like Mounjaro or Wegovy?
GLP-1 medications like Mounjaro (tirzepatide) and Wegovy (semaglutide) reduce appetite naturally, so you may find it easier to maintain a calorie deficit regardless of macro split. Focus on nutrient-dense foods and adequate protein to protect muscle. Your prescriber can advise on nutrition alongside medication.
How do I track my macros in the UK without complicated tools?
Use free apps like MyFitnessPal or Cronometer to log meals — they automatically calculate macros. Alternatively, follow simple guidelines: fill half your plate with vegetables, one quarter with protein, one quarter with carbs, and add a small amount of healthy fat. This rough approach works well for most people.
Is higher protein better for weight loss?
Yes — higher protein (1.6–2.2g per kg body weight) is particularly beneficial for weight loss because it increases satiety, preserves muscle mass, and has the highest thermic effect. However, you still need adequate carbs and fats for energy, hormones, and overall health.
Can I lose weight without counting macros at all?
Yes. Many people successfully lose weight using simpler approaches: eating whole foods, reducing processed items, controlling portion sizes, and increasing physical activity. Macro tracking helps some people, but it's not essential. Find the approach you can sustain long-term — that's what matters most.
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.