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 Month?
Healthy weight loss in the UK typically means losing 0.5 to 1 kg (1 to 2 lbs) per month, according to NHS guidance. This gradual approach helps you lose fat while preserving muscle mass and makes lasting lifestyle changes more sustainable. The speed of your weight loss depends on your starting weight, BMI, age, and how much you reduce your daily calorie intake. Faster weight loss is possible but carries greater risks, including nutrient deficiency and loss of lean muscle. Your GP can advise on what's safe for your individual circumstances.
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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.
Understanding Healthy Weight Loss Within BMI Framework
The NHS recommends a weight loss of 0.5 to 1 kg per week (approximately 2 to 4 kg per month) for sustainable results. This translates to a calorie deficit of around 500 to 1,000 calories per day. To understand what healthy weight loss means for you personally, it helps to know your current BMI and your ideal body weight range.
A healthy BMI sits between 18.5 and 24.9 according to NHS guidelines. If your current BMI is higher, you're moving towards a healthier weight with each kilogramme lost. For example, an adult who is 1.75m tall with a current weight of 90kg (BMI 29.4, overweight) could reach the healthy weight range by losing weight to approximately 75kg (BMI 24.5). At the recommended NHS rate of 0.5 to 1 kg per week, this could take 15 to 30 weeks.
Very gradual weight management (more than 1.5 kg per week) without medical supervision is not recommended, as it increases the risk of dehydration, nutrient deficiency, and loss of muscle tissue. Using our free BMI calculator, you can determine your current BMI and the healthy weight range for your height instantly.
Clinically BackedWeight Loss
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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.
Setting Your Personal Healthy Weight Target
Your ideal body weight range isn't a single number — it's a range based on your height and BMI. For most adults, the healthy weight range corresponds to a BMI of 18.5 to 24.9. South Asian, Chinese, Black African, and Black Caribbean adults should aim for a BMI between 18.5 and 22.9 due to higher health risks at higher BMI levels.
Once you know your healthy weight range, you can calculate a realistic monthly goal. If you have 20kg to lose and aim for 2 to 4 kg per month, you could reach your target within 5 to 10 months. This timeline is realistic and sustainable. Combining a reduced-calorie diet with increased physical activity typically produces better results than diet alone. Track your progress monthly using our free progress tracker to stay motivated and accountable.
- 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.
How much weight is it safe to lose in one month?
The NHS recommends losing 0.5 to 1 kg per week, which equals approximately 2 to 4 kg per month. This rate is considered safe and sustainable for most adults. Weight loss faster than this may result in muscle loss and nutrient deficiencies. Your GP can advise if a different rate is appropriate for your individual health situation.
How do I know what my healthy weight should be?
Your healthy weight range corresponds to a BMI of 18.5 to 24.9 (or 18.5 to 22.9 for South Asian and certain other ethnic backgrounds). Use our free BMI calculator to find your healthy weight range for your height. Your GP can also discuss personalised targets based on your medical history and fitness level.
Why does weight loss slow down over time?
As you lose weight, your body requires fewer calories to function, so the same calorie deficit produces slower weight loss. This is metabolic adaptation. Additionally, initial weight loss includes water and glycogen, which is faster than fat loss. Continuing with exercise and dietary consistency helps maintain progress despite this natural slowdown.
Can I lose weight faster with medication like Mounjaro or Wegovy?
Prescription weight loss medications like Mounjaro (tirzepatide) and Wegovy (semaglutide) may support faster weight loss when combined with dietary changes and exercise. Clinical trials showed average weight loss of 15 to 21 percent with Mounjaro and around 15 percent with Wegovy. These medications require a prescription and clinical assessment from your GP or a registered prescriber.
Is losing weight quickly ever recommended?
Very gradual weight management (more than 1.5 kg per week) is only recommended under medical supervision, typically in specialist weight management services. Rapid loss increases risks including muscle loss, gallstones, and nutrient deficiency. NHS guidance emphasises that slow, steady weight loss of 0.5 to 1 kg per week is most sustainable and protective of your health long-term.
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.