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 Does Keto Support Weight Loss?
The ketogenic (keto) diet can support weight loss by shifting your body into ketosis, where it burns fat for energy instead of carbohydrates. This metabolic change often reduces appetite and food cravings, helping many people achieve a calorie deficit naturally. However, keto isn't the only approach to weight management in the UK — the NHS recommends sustainable dietary changes combined with physical activity, and prescription weight loss medication may be an option for eligible adults. Use our free BMI calculator above to assess your current weight status and understand what a healthy weight range looks like for your height.
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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 Keto Works for Weight Loss
The ketogenic diet typically involves reducing carbohydrates to below 50g per day, forcing your body to enter ketosis — a metabolic state where fat becomes the primary fuel source instead of glucose. This shift can lead to rapid initial weight loss, particularly from water weight loss and reduced appetite.
- Appetite suppression: Ketones (produced during fat burning) and higher fat and protein intake naturally reduce hunger signals
- Calorie deficit: Lower appetite often results in eating fewer calories without conscious restriction
- Blood sugar stability: Removing carbohydrate spikes can reduce cravings and energy crashes
- Initial results: Many people see weight loss within the first 2–4 weeks, though this includes water weight loss
However, long-term success depends on whether you can sustain the diet. NHS weight management UK guidance emphasises that sustainable approaches — those you can stick with long-term — produce the best results. If keto feels too restrictive for you, the NHS and private prescribers offer alternative weight loss options including prescription medications and structured support programmes.
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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.
Keto vs. Other Weight Loss Approaches
Keto can be effective short-term, but adherence is challenging for many people. The NHS weight loss approach prioritises sustainable dietary changes — typically a moderate calorie deficit of around 500 kcal daily, supporting loss of 0.5–1 kg per week. This is more flexible and easier to maintain long-term than strict keto.
Other weight management options include:
- Mediterranean diet (strong NHS evidence for cardiovascular health)
- Intermittent fasting (16:8 or 5:2 patterns)
- Prescription weight loss medication like GLP-1 weight loss injections
- NHS tier 3 specialist weight management services with dietary support
Try our free GLP-1 weight loss calculator to explore whether prescription weight management might complement your efforts. Your GP can discuss which approach is right for your individual circumstances.
- 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.
How quickly does weight loss happen on keto?
Most people see 1–2 kg loss in the first week, mostly water weight. After that, fat loss typically averages 0.5–1 kg per week if a calorie deficit is maintained. Speed varies based on individual metabolism, starting weight, and how strictly you follow the diet.
Is keto sustainable long-term?
For some people, yes — but studies suggest many find it difficult to maintain beyond 6–12 months due to restrictiveness. The NHS recommends dietary approaches you can sustain for life. If keto doesn't feel sustainable for you, consider balanced alternatives or speak to your GP about prescription weight management options.
Can I combine keto with prescription weight loss medication?
Potentially, but this requires medical assessment. Some prescription weight loss medications may interact with ketogenic dieting or affect your electrolyte balance. Always inform your prescriber if you're following keto. They can advise on safe combinations or recommend alternative dietary approaches.
What's the difference between keto and low-carb dieting?
Keto is a specific low-carb approach (typically under 50g carbs daily) designed to achieve ketosis. Low-carb diets are more flexible, usually allowing 50–130g carbs daily. Low-carb approaches often feel more sustainable for long-term weight management UK than strict keto.
Does keto work if I have type 2 diabetes?
Keto may support blood sugar control in type 2 diabetes, but it requires medical supervision — medications may need adjusting. Never change your diet significantly without informing your GP first. Your prescriber can assess whether keto is appropriate for your individual health situation and medications.
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.