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 Much Weight Should You Lose Per Week in Kg?
The NHS recommends losing between 0.5 and 1 kg per week for safe, sustainable weight loss. This gradual approach helps protect muscle mass, maintain energy levels, and build lasting healthy habits. Faster weight loss is possible with medical support, but losing more than 1.5 kg per week without professional guidance increases the risk of nutritional deficiencies, muscle loss, and weight regain. Individual results vary based on your starting weight, metabolism, diet, and activity level. Your GP can provide personalised guidance on what a healthy weight loss rate means for you.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 to Achieve Safe Weight Loss of 0.5–1kg Per Week
To lose approximately 0.5 kg per week, you need to create a calorie deficit of around 3,500 kcal per week, which equals roughly 500 kcal per day. To lose 1 kg per week, aim for a deficit of around 7,000 kcal weekly (approximately 1,000 kcal daily). This can be achieved through a combination of dietary changes and increased physical activity.
Practical methods to create a calorie deficit:
- Reduce portion sizes and choose lower-calorie alternatives to foods you enjoy
- Increase physical activity — aim for at least 150 minutes of moderate exercise per week
- Reduce sugary drinks, alcohol, and ultra-processed foods
- Eat more protein and fibre to feel fuller for longer
- Track your food intake using a food diary or app to stay aware of calorie consumption
Weight loss medications like GLP-1 injections (such as Mounjaro or Wegovy) can support this process by reducing appetite alongside dietary and lifestyle changes. Track your weight loss progress weekly using our free progress tracker to monitor whether you're on target.
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.
Factors That Affect Your Ideal Weight Loss Rate
Not everyone can or should aim for exactly 1 kg per week. Several factors influence your healthy weight loss rate: starting weight (people with higher starting weights may lose faster initially), age (metabolism slows with age), muscle mass (more muscle increases calorie burn), medical conditions (thyroid issues, PCOS, diabetes affect weight loss), and medications (some medications slow metabolism). Women may lose weight slightly more slowly than men due to hormonal differences. Your ethnicity also matters — for South Asian, Chinese, Black African, and Black Caribbean adults, the NHS recommends lower BMI thresholds, which may affect weight loss goals. Use our free BMI calculator and healthy weight range tool to understand what's realistic 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.
Is losing 1kg per week safe?
Yes, losing 1 kg per week is within the NHS safe weight loss range. However, this rate requires a calorie deficit of approximately 1,000 kcal daily, which some people find unsustainable. If you struggle to maintain this, 0.5 kg per week (500 kcal daily deficit) is equally healthy and often easier to stick with long-term.
Why shouldn't I lose weight faster than 1.5kg per week?
gradual weight management (>1.5 kg per week) increases risks of muscle loss, nutritional deficiencies, gallstones, and hormonal imbalances. It's also harder to maintain — most people regain weight quickly after very rapid loss. Gradual loss helps preserve muscle mass and builds sustainable habits.
Does weight loss speed vary by person?
Yes. Your starting weight, age, metabolism, hormones, medical conditions, and genetics all affect how quickly you lose weight. Women may lose slightly slower than men. People with higher starting weights often see faster initial loss. Your GP can advise on realistic expectations for you.
How do I track if I'm losing weight at a healthy rate?
Weigh yourself weekly at the same time (ideally morning, after the toilet, before eating). Use our free progress tracker to log weekly weight and spot trends. Expect some weekly variation — focus on the overall direction over 2–4 weeks rather than daily fluctuations.
Can weight loss injections help me lose 0.5–1kg per week?
Yes. GLP-1 medications like Mounjaro and Wegovy work alongside calorie reduction and exercise to support weight loss at this rate. Use our free GLP-1 weight loss calculator to estimate potential weight loss with medication at different doses — individual results vary significantly.
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.