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
What Is The Average Weight Loss Per Week?
The NHS recommends losing between 0.5 and 1 kg (1–2 lbs) per week as a safe, sustainable rate for weight loss. This pace helps you lose fat while preserving muscle mass and making lasting lifestyle changes. Weight loss speed depends on several factors including your starting weight, age, metabolism, activity level, and whether you're using medication or lifestyle changes alone. Understanding what constitutes healthy, average weight loss helps you set realistic goals and track progress effectively without putting your health at risk.
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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 NHS Guidelines Define Healthy Weight Loss
The NHS recommends a weight loss of 0.5–1 kg per week (approximately 1–2 lbs) as the safest and most sustainable approach. This rate typically requires a calorie deficit of around 500 kcal per day, since 1 kg of body weight is roughly equivalent to 7,700 kcal. Losing weight faster than this (more than 1.5 kg per week) can result in greater muscle loss, nutritional deficiencies, and is harder to sustain long-term.
- Safe rate: 0.5–1 kg per week (1–2 lbs)
- Required calorie deficit: Approximately 500 kcal per day
- Typical time to lose 5% body weight: 5–10 weeks for most people
- Faster loss (>1.5 kg/week): Only under medical supervision
Weight loss is not always linear — you may lose more in the first 1–2 weeks (often water weight) and then settle into a steadier pace. Using our free BMI calculator can help you determine your healthy weight range for your height, giving you a realistic target to work towards at this sustainable rate.
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 Personal Weight Loss Rate
Your individual weight loss speed depends on multiple factors beyond just calorie intake. Starting weight matters significantly: people with more weight to lose often lose faster initially. Age, sex, metabolism, fitness level, and muscle mass all influence how quickly your body responds to a calorie deficit. Medical conditions like thyroid problems, PCOS, and type 2 diabetes can slow progress. Medications including some antidepressants and blood pressure tablets may also affect weight loss rate.
For personalised guidance on what healthy weight means for your specific height and age, use our free BMI calculator and weight converter above to find your healthy weight range. Tracking your progress weekly using our free progress tracker helps you spot patterns and stay motivated, even if some weeks show no change — this is completely normal and not a sign of failure.
- 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 1 kg per week realistic for everyone?
No. Average healthy loss is 0.5–1 kg per week, but individual rates vary based on starting weight, age, metabolism, and medical factors. People with significant weight to lose may lose faster initially, while those closer to a healthy weight often lose more slowly. Your GP can advise on what's realistic for you personally.
What counts as the average UK weight loss on a diet?
Average sustainable weight loss is 0.5–1 kg per week on a calorie-controlled diet. Most people achieve this through a 500 kcal daily deficit. The actual amount you lose depends on your diet approach, activity level, and individual metabolism. gradual weight management programmes may promise faster results but are harder to maintain long-term.
How do I calculate what my healthy weight should be?
Use our free BMI calculator on this page to find your healthy weight range. For adults, a healthy BMI is 18.5–24.9, which translates to specific kg and stone ranges depending on your height. If you have South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds (18.5–22.9) apply. Your GP can also advise on ideal body weight for your individual circumstances.
Can weight loss injections help me lose weight faster?
GLP-1 medications like Mounjaro and Wegovy may support weight loss alongside diet and exercise. Clinical trials showed average weight loss of 14–21% body weight over several months — faster than diet alone in many cases. However, these are prescription-only medicines requiring clinical assessment. Your prescriber will assess whether medication is appropriate for you and combine it with lifestyle changes.
Why am I not losing weight at the average rate?
Weight loss is not always linear — some weeks show no change despite being in a calorie deficit. This can be due to water retention, hormonal cycles, muscle gain, or plateaus. If you've not lost weight for 4+ weeks despite consistent effort, speak to your GP to rule out medical causes. Tracking weekly using our progress tracker helps you spot longer-term trends rather than focusing on single-week fluctuations.
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.