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 in Kg?
The NHS recommends losing weight at a rate of 0.5 to 1 kg per week, which translates to roughly 2 to 4 kg per month for sustainable, healthy results. This pace is considered safe and effective because it preserves muscle mass, maintains metabolism, and allows your body to adjust gradually. Faster weight loss may occur initially, but the NHS advises against aiming for more than 1 kg weekly without medical supervision. The ideal body weight depends on your height and individual health—use your healthy weight range based on your BMI (18.5–24.9) as your target, rather than a specific monthly figure.
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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.
Healthy Weight Loss Rate and Your BMI Target Range
The healthy weight loss rate according to NHS guidelines is 0.5 to 1 kg per week, which equals approximately 2 to 4 kg per month. This moderate pace helps preserve lean muscle, maintains your resting metabolic rate, and allows behavioural and dietary habits to embed sustainably.
To find your personal weight loss target, calculate your healthy weight range using BMI. A healthy BMI is 18.5–24.9. For example, an adult who is 1.70m (5ft 7in) tall has a healthy weight range of approximately 53–72 kg (8st 5lbs to 11st 4lbs). Use our free BMI calculator above to determine your healthy weight range based on your height—this becomes your realistic target, not a monthly quota.
- 0.5–1 kg per week = sustainable, muscle-preserving loss
- 1.5+ kg per week = risks muscle loss and metabolic slowdown (requires medical supervision)
- Very low-calorie diets (<800 kcal/day) = NHS recommendation only under medical supervision
A calorie deficit of approximately 500 kcal per day typically results in losing 0.5 kg weekly. Individual factors—age, gender, activity level, metabolism—all affect your personal rate.
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.
Using BMI to Set Realistic Monthly Weight Loss Goals
Rather than fixating on a fixed monthly target, align your weight loss goal with your healthy weight range based on your BMI. This approach is more sustainable and health-focused than arbitrary monthly numbers.
Start by calculating your current BMI and identifying your target BMI range (18.5–24.9 for most adults; 18.5–22.9 for South Asian, Chinese, Black African, or Black Caribbean adults). If you're significantly above this range, you may realistically lose 2–4 kg per month initially, then slower as you approach your target.
Track your progress monthly using our free progress tracker to stay motivated without becoming obsessed with weekly fluctuations. Weight naturally varies by 1–2 kg day-to-day due to water retention, food volume, and hormones. Focus on the trend over 4 weeks rather than daily changes. Your GP or a registered dietitian can personalise your rate based on your medical history, medications, and health conditions.
- 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 2–4 kg per month healthy?
Yes, this aligns with NHS guidance of 0.5–1 kg weekly. This rate preserves muscle, maintains metabolism, and supports sustainable lifestyle change. Faster loss risks muscle loss and metabolic slowdown, requiring medical supervision.
How do I know my target weight based on BMI?
Calculate your healthy BMI range (18.5–24.9) using your height. For example, at 1.75m tall, healthy weight is roughly 56–76 kg (8st 12lbs to 12st). Use our free BMI calculator above to find your personalised range instantly.
Why does weight loss slow down after the first month?
Initial loss often includes water weight. As you continue, loss slows to roughly 0.5–1 kg weekly. This is normal and healthy. Metabolism may also adapt slightly, but consistent calorie deficit maintains steady progress.
Does waist measurement matter as much as monthly weight loss?
Yes. Waist circumference (over 94cm for men, 80cm for women = increased risk) is a strong health indicator independent of weight. You can lose cm without changing kg if gaining muscle, so track both metrics.
Should I aim for weight loss every single month?
No. Sustainable weight loss involves gradual changes. Some months may show no change due to hormones, water retention, or muscle gain—yet fat loss continues. Weight loss isn't always linear; monthly progress matters less than 3–6 month trends.
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.