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
Average Weight Loss Per Week — What's Safe and Sustainable?
The NHS recommends losing weight at a rate of 0.5 to 1 kg (1 to 2 lbs) per week for sustainable, healthy results. This gradual approach helps preserve muscle mass, reduces the risk of nutritional deficiencies, and is far more likely to lead to long-term success than gradual weight management. However, the actual rate of weight loss varies significantly between individuals depending on starting weight, metabolic rate, diet quality, activity level, and whether you're using weight loss support like medication alongside lifestyle changes. Understanding your personal healthy weight range and what factors influence your progress is key to setting realistic expectations.
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 Much Weight Should You Lose Per Week?
The NHS safe weight loss target is 0.5–1 kg (1–2 lbs) per week. This equates to a calorie deficit of approximately 500–1,000 kcal per day. To achieve this, you typically need to reduce your daily calorie intake and increase physical activity.
- 0.5 kg per week: Requires a 500 kcal daily deficit — suitable for most people and very sustainable
- 1 kg per week: Requires a 1,000 kcal daily deficit — achievable but more demanding; often combines diet and exercise
- Faster than 1 kg/week: Only recommended under medical supervision (e.g., very low calorie diets, weight loss medication); increases risk of muscle loss, gallstones, and nutritional deficiency
Use our free BMI calculator above to find your healthy weight range for your height, then calculate the calorie deficit needed to reach it. For most people, aiming for 0.5 kg per week is the sweet spot — sustainable, safe, and psychologically easier to maintain.
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 Weight Loss Speed
Weight loss is not uniform across individuals. Starting weight matters: people with higher starting weights often lose faster initially due to larger calorie deficits. Age and metabolism: metabolic rate typically decreases with age, slowing weight loss. Muscle mass and frame size: individuals with more muscle burn more calories at rest. Ethnicity and genetics: genetic factors and ethnicity influence metabolic efficiency and fat distribution. Medical conditions: thyroid disorders, polycystic ovary syndrome (PCOS), and other conditions can slow weight loss despite calorie deficit. Sex hormones, stress, sleep quality, and medication also play roles. Our free progress tracker helps you log weekly changes and identify your personal pattern over time.
- 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 1 kg per week weight loss realistic?
Yes, 1 kg per week is achievable and safe for most people when combined with diet and exercise creating a 1,000 kcal daily deficit. However, this is demanding and not everyone can sustain it long-term. The NHS emphasizes that 0.5 kg per week is often more sustainable and just as effective over months.
Will I lose weight faster with weight loss medication like Mounjaro or Wegovy?
Weight loss medications can support faster results alongside diet and exercise. Clinical trials showed average losses of 15–21% body weight with tirzepatide (Mounjaro) over 72 weeks, though individual results vary. These are prescription-only medicines requiring clinical assessment from a prescriber.
Why does weight loss slow down after initial weeks?
Initial rapid loss includes water and glycogen; after 2–3 weeks, loss typically settles at a slower rate reflecting fat loss. Your body also adapts metabolically to reduced calories, slightly lowering energy expenditure. This plateau is normal and expected.
Can I work out my healthy weight range myself?
Yes — use our free BMI calculator on this page to find your healthy weight range instantly. Healthy BMI is 18.5–24.9 for most adults; South Asian, Chinese, and Black African adults have lower thresholds (18.5–22.9). Your GP can also provide personalised guidance.
What if I'm not losing 0.5–1 kg per week despite dieting?
Weight loss varies individually due to metabolism, muscle mass, medical conditions, and medication. If you're losing consistently at 0.25–0.5 kg weekly, you're still making progress. Consult your GP if weight loss has stopped entirely despite calorie deficit — they can check for underlying health factors. ```
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.