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
Diet Chart For Quick Weight Loss — What Works in the UK
Quick weight loss is possible, but safety matters more than speed. The NHS recommends losing weight at a rate of 0.5 to 1 kg per week for sustainable, healthy results. gradual weight management can lead to muscle loss, nutritional deficiencies, and weight regain. This guide explains evidence-based diet approaches used in the UK, safe calorie deficits, and when prescription weight loss medication like GLP-1 injections may support your goals alongside dietary changes. Understanding your BMI and calorie needs is the essential first step.
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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.
How Fast Weight Loss Diets Work — NHS Guidance
Quick weight loss happens when you create a calorie deficit — consuming fewer calories than your body uses. A deficit of 500 kcal per day typically results in approximately 0.5 kg weight loss per week, which aligns with NHS recommendations. Very low calorie diets (under 800 kcal daily) can produce faster results but should only be followed under medical supervision and are typically used in specialist weight management services.
- Standard approach: 500 kcal daily deficit = 0.5 kg/week loss
- Moderate approach: 750 kcal daily deficit = 0.75 kg/week loss
- Aggressive approach: 1000 kcal daily deficit = 1 kg/week loss (not recommended without medical support)
The fastest safe method combines reduced-calorie eating with increased physical activity. Prescription weight loss medication can support quicker results when used alongside lifestyle changes. Use our free BMI calculator above to establish your current starting point and healthy weight range for your height.
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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.
Sustainable Diet Approaches vs. gradual weight management
Popular quick weight loss diet patterns in the UK include low carbohydrate diets, intermittent fasting (16:8 or 5:2 methods), and structured meal replacements. While these can produce faster initial results, the most sustainable approach combines modest calorie restriction with increased activity. Evidence shows that diets aligned with the Mediterranean pattern offer long-term health benefits beyond weight loss alone.
For adults with weight management uk concerns, consider consulting your GP about eligibility for prescription weight loss support. GLP-1 medications like Wegovy (semaglutide) are available through NHS weight management services or private prescribing and may help accelerate results when combined with diet. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different doses if you're considering this option.
- 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.
What is the safest rate of weight loss according to the NHS?
The NHS recommends losing 0.5 to 1 kg per week (1 to 2 lbs). This rate is sustainable, preserves muscle mass, and reduces nutritional deficiency risk. Faster loss is possible under medical supervision but may lead to muscle loss and weight regain. Your GP can advise on safe rates for your individual circumstances.
Can I lose 1 stone in a month safely?
Losing 1 stone (6.35 kg) in one month would require an extreme calorie deficit and is not considered safe without medical supervision. This would equate to approximately 1.5 kg per week. The NHS recommends slower, sustained loss. If gradual weight management is medically necessary, discuss options with your GP or a specialist weight management service.
What's the difference between a diet chart and prescription weight loss medication?
A diet chart is a self-managed eating plan based on calorie targets and food choices. Prescription weight loss medications like GLP-1 injections (Wegovy, Mounjaro) work by reducing appetite and supporting fullness alongside dietary changes. Medications are prescription-only and require clinical assessment. Both approaches work best combined with increased activity.
Is quick weight loss better for health outcomes than slow weight loss?
No. Research shows that steady, moderate weight loss (0.5–1 kg/week) produces better long-term health outcomes than rapid loss. Slow weight loss preserves muscle, reduces micronutrient deficiencies, and is more likely to be maintained. Even a 5% reduction in body weight improves blood pressure, blood sugar, and cholesterol — regardless of speed.
How do I know if I'm eligible for prescription weight loss medication in the UK?
Eligibility typically requires a BMI of 30 or above, or 27 or above with weight-related health conditions (diabetes, hypertension, sleep apnoea). Access through the NHS requires referral to a specialist tier 3 weight management service. Private prescribing is available without NHS referral but requires a clinical assessment. Use our BMI calculator to check your current BMI and discuss options with your GP.
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.