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
How The Ketogenic Diet Supports Weight Loss
The ketogenic diet is a low-carbohydrate, high-fat eating plan that shifts your body into ketosis, a metabolic state where fat becomes the primary fuel source. Many UK adults use keto for weight management, though results vary significantly between individuals. Understanding how ketogenic eating works, its potential benefits, and how it compares to other weight loss approaches can help you decide if it's right for you. Use our free BMI calculator to check your current weight status before making any dietary changes.
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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.
How The Ketogenic Diet Works For Weight Loss
The ketogenic diet works by dramatically reducing carbohydrate intake — typically to under 50g daily — forcing your body to enter ketosis. In this metabolic state, your liver breaks down fat into ketones, which replace glucose as the brain's primary fuel. This shift may help reduce appetite and food cravings, potentially supporting a calorie deficit without constant hunger.
- Appetite suppression: Ketones and increased protein intake may signal fullness more effectively than high-carb diets
- Rapid initial water loss: Lower carbs mean reduced glycogen storage, resulting in quick early weight loss (largely water weight)
- Metabolic changes: Some research suggests keto may increase fat oxidation, though total calorie intake remains the key factor for sustainable loss
- Blood sugar stability: Reduced carbs may help stabilise blood glucose, potentially reducing cravings for sugary foods
The NHS emphasises that sustainable weight loss requires consistent calorie deficit. A typical target is 0.5–1 kg per week. Keto can help some people achieve this by naturally reducing overall food intake, but individual responses vary significantly.
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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.
Ketogenic Diet vs Other Weight Management Approaches
The ketogenic diet is one of many weight loss approaches available in the UK. For weight management uk, the NHS recommends approaches you can sustain long-term — including balanced calorie reduction, intermittent fasting, and Mediterranean-style eating. Keto works well for some people but is restrictive and may not suit everyone.
Prescription weight loss medication such as GLP-1 injections may be appropriate if you have a BMI of 30 or above, or 27 or above with weight-related health conditions. These medications work through different mechanisms — activating hormones that regulate appetite — and may be combined with any dietary approach. Our GLP-1 weight loss calculator can help you explore potential outcomes with prescription support alongside diet changes.
To track your progress with any weight loss method — including ketogenic eating — try our free progress tracker to log weight, measurements, and dietary changes over time. Remember that weight loss is rarely linear; fluctuations of 1–2 kg are normal due to water retention, hormones, and digestion timing.
- 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.
Is the ketogenic diet safe for long-term weight loss?
Keto can support short- to medium-term weight loss effectively for many people. However, long-term safety remains debated — some research suggests potential concerns with cholesterol levels and nutrient deficiencies if not carefully planned. Always consult your GP before starting any restrictive diet, especially if you have existing health conditions. A registered dietitian can help ensure adequate nutrition.
How much weight can I expect to lose on a ketogenic diet?
Initial losses are often rapid (1–3 kg in the first week) due to water weight from reduced carbs. Sustainable fat loss typically follows at 0.5–1 kg per week, depending on calorie deficit and individual metabolism. Results vary significantly — some people lose steadily, others plateau. Total calorie intake remains the primary driver of weight loss, not diet type alone.
Can I combine a ketogenic diet with weight loss injections like GLP-1 medication?
Yes — prescription weight loss medications such as Wegovy (semaglutide) or Mounjaro (tirzepatide) can be combined with any dietary approach, including keto. However, this must be managed with your prescriber. GLP-1 medications slow gastric emptying, which may affect how you tolerate very restrictive eating patterns. Your healthcare provider can advise on the best combination for you.
Does the NHS recommend the ketogenic diet for weight loss?
The NHS does not specifically endorse keto as a primary weight loss method. NHS guidance emphasises sustainable approaches you can maintain long-term, including balanced calorie reduction and Mediterranean-style eating. However, if keto helps you achieve a consistent calorie deficit, it can support your weight management goals. Always inform your GP of significant dietary changes.
What's the difference between ketogenic diet weight loss and medication-based weight loss?
Ketogenic diet relies on restricting carbohydrates to create appetite suppression and calorie deficit through dietary choice. Prescription weight loss medications work by activating natural appetite-regulating hormones in your brain and gut. Keto requires strict adherence; medications may feel more effortless. Both require calorie deficit to work. Some people combine both approaches under medical supervision for improved results.
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.