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
Does Grapefruit Help With Weight Loss?
Grapefruit is often promoted as a weight loss superfood, but the evidence is limited. Whilst grapefruit contains nutrients and fibre that may support healthy eating, it's not a clinically supported solution for weight management. The truth is that sustainable weight loss in the UK requires consistent dietary changes, increased physical activity, and sometimes medical support. If you're considering weight loss, understanding what actually works — and what doesn't — is essential for long-term success.
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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.
What Does the Research Actually Show?
Studies on grapefruit and weight loss show modest, inconsistent results. A small 2006 study suggested that grapefruit consumption may have a minor effect on weight loss, but findings have not been consistently replicated. The proposed mechanism involves compounds in grapefruit that might slightly affect metabolism or reduce appetite, but any effect is marginal compared to overall calorie balance.
The reality is that no food — including grapefruit — can compensate for a calorie surplus. Weight loss fundamentally depends on consuming fewer calories than you burn. Grapefruit is nutritious (rich in vitamin C, fibre, and antioxidants) and can be part of a healthy diet, but it won't create the calorie deficit needed for meaningful weight loss. The NHS emphasises that sustainable weight management requires consistent dietary changes and physical activity, not reliance on specific foods.
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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.
Evidence-Based Weight Loss Strategies That Actually Work
If you're seeking effective weight management in the UK, focus on approaches with strong evidence: a consistent calorie deficit of around 500 kcal per day typically results in losing approximately 0.5 kg per week. The NHS Weight Loss Plan supports behaviour change, dietary modification, and increased physical activity as the foundation. For some adults, prescription weight loss medication — such as GLP-1 injections like Wegovy or dual GIP/GLP-1 medications like Mounjaro — may be appropriate following clinical assessment. Try our free BMI calculator and GLP-1 weight loss calculator to understand your starting point and explore evidence-based options that may suit your situation.
- 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 eating grapefruit speed up metabolism?
There's no solid evidence that grapefruit significantly speeds up metabolism. Whilst grapefruit contains some compounds that may have minor metabolic effects, these are too small to create meaningful weight loss on their own. Weight loss depends primarily on overall calorie balance, not on metabolism-boosting foods.
Can grapefruit interact with weight loss medication?
Yes — grapefruit can interact with some medications, including certain prescription weight loss treatments. If you're taking any medication, including GLP-1 injections like Wegovy, always inform your GP or prescriber about grapefruit consumption, as it may affect how medications are processed by your body.
Is grapefruit good to include in a weight loss diet?
Grapefruit can be a healthy addition to a balanced diet because it's low in calories, high in fibre, and rich in vitamins. However, it's not a weight loss food itself. What matters is your total calorie intake and maintaining a consistent deficit. Grapefruit may help you feel fuller due to its fibre content, but it won't create weight loss on its own.
What's more effective for weight loss — grapefruit or prescription medication?
Prescription weight loss medications like Wegovy have much stronger evidence. Clinical trials showed Wegovy helps participants lose an average of around 15% of body weight over 68 weeks — far more significant than any effect from grapefruit. However, medication works alongside diet and exercise, not instead of them. Your GP can assess whether prescription treatment is appropriate for you.
How much weight can I realistically lose with diet and exercise alone?
The NHS recommends losing 0.5–1 kg per week, which is sustainable and healthy. This requires a calorie deficit of around 500 kcal daily. Many people lose 5–10% of their body weight through consistent dietary changes and physical activity. For weight loss support in the UK, use our BMI calculator to assess your current position and speak with your GP about the best approach for you.
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.