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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1000 Kcal a Day Weight Loss in the UK
A 1000 kcal per day diet is a very low-calorie diet (VLCD) that should only be followed under medical supervision in the UK. While such restrictive intake can produce gradual weight management, it carries risks including muscle loss, nutritional deficiency, and metabolic changes. If you're considering this approach, prescription weight management options and NHS weight loss support may offer safer, more sustainable alternatives. Your GP can assess what's right for your individual health needs and discuss whether you're eligible for prescription medication or specialist weight management services.
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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.
UK Prescription Weight Loss Options for gradual weight management
For adults seeking effective weight management in the UK, three prescription-only medications are licensed for weight loss and may offer a safer approach than extreme calorie restriction:
- Mounjaro (tirzepatide): A once-weekly GLP-1 and GIP dual receptor agonist. Clinical trials showed average weight loss of 15–21% of body weight alongside reduced-calorie diet and increased physical activity. Maximum dose is 15 mg weekly.
- Wegovy (semaglutide): A once-weekly GLP-1 receptor agonist. Evidence shows average weight loss of approximately 15% of body weight. Maximum maintenance dose is 2.4 mg weekly.
- Saxenda (liraglutide): A daily GLP-1 injection with similar mechanisms. Maximum dose is 3 mg daily.
These medications work by reducing appetite and supporting feeling fuller after smaller meals. Individual results vary significantly, and all are most effective when combined with dietary changes and physical activity. Each requires a prescription from a UK-licensed healthcare professional following clinical assessment of your eligibility and health profile.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
NHS vs Private: How to Access Weight Loss Medication in the UK
In the UK, prescription weight loss medication is available through two routes:
- NHS: Access is through specialist tier 3 or tier 4 weight management services. You'll need a referral from your GP, and availability varies significantly by region. Waiting lists can be lengthy in many areas, sometimes several months to over a year.
- Private: Available through GPhC-registered online pharmacies following an online consultation with a UK-licensed prescriber. No NHS referral needed, but costs typically range from £129–£320+ monthly depending on medication and dose.
Speak with your GP about which route suits your circumstances. They can assess your eligibility, discuss whether prescription medication is appropriate for you, and explain what support is available locally. Use our free weight loss calculator to estimate potential outcomes with GLP-1 medication, and our BMI calculator to understand your current weight category and health context.
- 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 a 1000 kcal a day diet safe in the UK?
No — not without medical supervision. The NHS recommends a safe weight loss rate of 0.5–1 kg per week, typically achieved through a 500 kcal daily deficit. VLCDs (under 800 kcal/day) should only be followed under specialist medical supervision due to risks of muscle loss, nutritional deficiency, and metabolic disruption. Your GP can advise whether a medically supervised VLCD is appropriate for your situation.
How much weight can you lose on 1000 calories a day?
On 1000 kcal/day, you might lose 1–2 kg per week initially, but this includes water weight and muscle loss, not just fat. gradual weight management is unsustainable and risks muscle breakdown, nutrient deficiencies, and metabolic slowdown. Prescription weight loss medication combined with a moderate calorie deficit offers safer, more sustainable results for many people.
What prescription weight loss medication is available on the NHS in the UK?
Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide) are licensed for weight management in the UK. NHS access is through specialist weight management services — you'll need a GP referral. Eligibility typically requires a BMI of 30+ or 27+ with weight-related health conditions. Regional availability varies significantly.
Can I get weight loss injections privately in the UK?
Yes. GLP-1 medications (Mounjaro, Wegovy, Saxenda) are available privately through GPhC-registered online pharmacies following consultation with a UK-licensed prescriber. This route doesn't require NHS referral but involves private costs. Always ensure you're using a legitimate, regulated pharmacy and that a proper clinical assessment is completed.
How much weight loss can I expect with prescription weight loss medication?
Clinical trials show average weight loss of 15–21% of body weight with GLP-1 or GIP/GLP-1 medications, though individual results vary significantly. Results are achieved alongside a reduced-calorie diet and increased physical activity — medication alone is not enough. Your prescriber can discuss realistic expectations based on your health profile and circumstances.
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.