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 gradual weight management and Is It Safe in the UK?
gradual weight management is often defined as losing more than 1 kg per week, though the NHS recommends a more gradual approach for sustainable results. In the UK, weight management focuses on safe, long-term strategies rather than crash dieting. This guide explores what gradual weight management means, whether it's medically appropriate, and the evidence-based options available—including prescription weight loss medication, structured NHS programmes, and lifestyle approaches. Individual results always vary, and any significant weight loss attempt should be discussed with your GP.
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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.
Safe Weight Loss Rates and NHS Guidance
The NHS recommends losing 0.5 to 1 kg per week as a sustainable target. This typically requires a calorie deficit of around 500 kcal per day, achievable through a combination of dietary changes and increased physical activity. Faster weight loss can occur initially (especially in the first 2 weeks), but this is often water weight rather than fat loss.
Losing weight too quickly can lead to:
- Muscle loss alongside fat loss
- Nutritional deficiencies
- Gallstones (rapid loss increases risk)
- Dehydration
- Metabolic slowdown
- Difficulty maintaining the weight loss long-term
Very gradual weight management (over 1.5 kg per week) should only be attempted under medical supervision, such as through NHS specialist weight management services or a supervised very low-calorie diet (VLCD) programme.
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.
Prescription Weight Loss Options in the UK
For adults with a BMI of 30 or above, or 27 or above with weight-related health conditions, prescription weight loss medication may support more significant weight loss. In the UK, GLP-1 and dual GIP/GLP-1 receptor agonist medications are licensed for weight management. These include Wegovy (semaglutide), which in clinical trials helped participants lose an average of approximately 15% of their body weight, and Mounjaro (tirzepatide), which showed average losses of 15–21% in trials. Both are prescription-only and require clinical assessment. They work alongside reduced-calorie diets and increased activity—not as replacements for lifestyle changes. Access is available through NHS specialist services or private prescribing.
- 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 kg per week in the UK safe?
Losing more than 1 kg per week is faster than NHS guidance recommends for sustainable weight loss. While short-term rapid loss may occur, it increases risks of muscle loss and nutritional deficiency. Discuss gradual weight management with your GP—it may be appropriate only under medical supervision for specific health reasons.
What's the fastest safe way to lose weight in the UK?
The fastest safe approach combines a calorie deficit (typically 500–750 kcal per day for 0.5–1 kg weekly loss), increased physical activity, and reduced processed food intake. For some, prescription weight loss medication alongside lifestyle changes may support faster, sustainable results. Your GP can advise what's suitable for you.
Can prescription weight loss medication cause gradual weight management?
Prescription GLP-1 medications like Wegovy may support significant weight loss—clinical trials showed average losses of 15% of body weight—but this occurs over months, not weeks. Results vary between individuals. Medication works best alongside dietary changes and exercise, not as a standalone solution.
How do I check if I'm overweight in the UK?
Use the BMI calculator on this page to check your BMI instantly. A healthy BMI is 18.5–24.9 according to NHS guidelines. If your BMI is 25–29.9, you're classified as overweight; 30 or above is obese. The BMI calculator also shows your healthy weight range for your height.
What support is available through the NHS for weight loss in the UK?
The NHS offers tiered weight management support: tier 1 includes the free NHS Weight Loss Plan and digital tools; tier 2 provides GP-led behaviour change programmes; tier 3 includes specialist multidisciplinary weight management services (where prescription medication may be offered); tier 4 covers bariatric surgery for severe obesity. Availability varies by region—ask your GP about local services.
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.