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 a Normal Weight Loss Rate?
The NHS recommends losing weight at a rate of 0.5 to 1 kilogramme (approximately 1 to 2 pounds) per week for sustainable, healthy results. This normal weight loss rate balances effectiveness with safety, helping you avoid muscle loss, nutrient deficiencies, and the fatigue that comes with crash dieting. Faster weight loss is possible with medical support, but gradual loss is more likely to become a lasting habit. Understanding what constitutes healthy weight for your height and age is equally important — use our free BMI calculator to find your current starting point and healthy weight range.
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.
NHS Guidelines and Safe Weight Loss Targets
The NHS standard is 0.5–1 kg per week, achieved through a calorie deficit of approximately 500–1,000 kcal per day. This translates to losing roughly 2–4 kg (4–9 lbs or approximately 0.3–0.6 stone) per month.
- At 500 kcal daily deficit: expect approximately 0.5 kg loss weekly
- At 1,000 kcal daily deficit: expect approximately 1 kg loss weekly
- Very low calorie diets (under 800 kcal/day) may achieve faster loss but should only be followed under medical supervision
- Crash dieting or extreme calorie restriction often leads to rapid loss of water and muscle, not fat — results are rarely sustainable
Average UK adults losing weight at the recommended rate typically see meaningful health improvements within 8–12 weeks, including lower blood pressure, improved blood sugar control, and reduced strain on joints.
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 Affecting Your Individual Weight Loss Rate
Weight loss speed varies between individuals based on age, metabolism, muscle mass, genetics, medications, and underlying health conditions. Younger people and those with more muscle typically lose weight faster. Women often lose weight slightly more slowly than men due to differences in muscle mass and hormones. Your healthy weight range — found using our weight converter and BMI calculator — depends on your height, age, and ethnicity. South Asian, Chinese, Black African, and Black Caribbean adults have different BMI thresholds according to NHS guidance. If you're taking medications like antidepressants or corticosteroids, weight loss may be slower. Always discuss your individual targets with your GP.
- 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 too fast?
No, 1kg per week is within NHS safe limits and achievable through a 1,000 kcal daily deficit alongside healthy eating and physical activity. However, not everyone can sustain this rate — 0.5kg weekly is equally healthy and often more sustainable long-term. Your GP can advise on the right pace for you.
How much weight can you lose in a month safely?
Safely, expect 2–4kg (4–9 lbs) per month at the recommended 0.5–1kg weekly rate. In the first month, initial loss may be higher due to water weight loss alongside fat loss. After month one, loss typically stabilises at the 2–4kg range.
Why is slow weight loss better than rapid loss?
Slow, steady loss preserves muscle mass, provides sustainable habit change, maintains energy levels, and avoids nutritional deficiencies. Rapid loss (more than 1.5kg weekly) often involves water and muscle loss, leaving you fatigued and prone to regaining weight quickly.
What affects how quickly you lose weight?
Age, sex, muscle mass, genetics, medications, underlying health conditions, and how strictly you follow dietary changes all affect loss speed. Some people naturally lose weight faster than others — individual variation is normal and expected.
Should I use a weight loss tracker to monitor my progress?
Yes — tracking progress helps identify what works for you and keeps you motivated. Our free progress tracker lets you log weight, date, and notes. Weigh yourself weekly or fortnightly at the same time of day for consistency, and remember that weight fluctuates daily due to water, food intake, and hormones.
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.