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
Treatments for Losing Weight in the UK
There are several effective treatments available to support sustainable weight loss in the UK, ranging from lifestyle-based programmes to prescription medications. The NHS recommends losing weight at a safe rate of 0.5 to 1 kg per week alongside reduced-calorie diet and increased physical activity. Your GP can help you explore options that suit your individual health needs, whether through self-help resources, community programmes, or specialist weight management services. Use our free BMI calculator to understand where you currently stand, and then explore the treatments best suited to your 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.
NHS Weight Management Pathways and Prescription Options
Weight loss in the UK is typically supported through a four-tier NHS pathway. Tier 1 includes self-help, digital tools, and community weight management programmes — these are free and available to all adults. Tier 2 involves primary care-based interventions, including the NHS Weight Loss Plan and behaviour change support from your GP practice. Tier 3 provides specialist multidisciplinary weight management services where prescription medications may be offered for eligible adults.
For weight loss UK, prescription treatments include GLP-1 receptor agonist injections — the most widely prescribed being Wegovy (semaglutide) and Mounjaro (tirzepatide). These are prescription-only medicines available through NHS specialist services or private online prescribing following clinical assessment. Clinical trials show these may help people lose an average of 15–21% of body weight alongside lifestyle changes, though individual results vary significantly. Tier 4 covers bariatric (weight loss) surgery for severe obesity with health complications.
Try our GLP-1 weight loss calculator to estimate potential outcomes at different doses if eligible for prescription treatment.
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.
Safe and Sustainable Weight Loss Methods
Lose weight safely by combining dietary changes with increased physical activity — the foundation of sustainable weight loss. A calorie deficit of approximately 500 kcal per day typically results in 0.5 kg per week loss. Evidence-based dietary approaches include the Mediterranean diet, intermittent fasting, and low-carbohydrate eating, though any method works best when you can sustain it long-term.
Even modest weight loss — just 5–10% of body weight — brings measurable health benefits including improved blood sugar control, lower blood pressure, and reduced joint pain. Weight loss support is available through your GP, NHS weight management programmes, and online communities. Track your progress with our free progress tracker to stay motivated and identify patterns in your weight loss journey.
- 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.
What is the fastest safe way to lose weight in the UK?
The NHS recommends losing 0.5–1 kg per week for sustainable, safe weight loss. This typically requires a calorie deficit of around 500 kcal daily plus physical activity. Very gradual weight management (over 1.5 kg/week) without medical supervision risks muscle loss and nutritional deficiency. Your GP can advise on safe approaches for your individual health.
Are prescription weight loss injections available on the NHS?
Yes. GLP-1 medications like Wegovy (semaglutide) and Mounjaro (tirzepatide) are available through NHS specialist tier 3 weight management services for eligible adults. Eligibility typically requires BMI 30+ or BMI 27+ with weight-related health conditions. Referral is through your GP. However, NHS availability and waiting times vary significantly by region. Private prescribing is also available through online clinical assessments.
How much weight can you lose with Wegovy or Mounjaro?
Clinical trials show Wegovy may help lose approximately 15% of body weight over 68 weeks, while Mounjaro may result in 15–clinically studied weight loss at higher doses. However, individual results vary considerably — some people lose more, some less. Weight loss is greatest when combined with a reduced-calorie diet and increased physical activity. Our GLP-1 calculator can estimate potential outcomes based on your circumstances.
What is the difference between lifestyle changes and medication for weight loss?
Lifestyle changes (diet and exercise) are the foundation of all sustainable weight loss and should always be the first approach. Prescription medications like GLP-1 injections are added for eligible adults when lifestyle changes alone have been insufficient, particularly if weight-related health conditions are present. Medications work best alongside — not instead of — dietary and activity changes.
How do I access NHS weight management support?
Start by speaking with your GP, who can refer you to your local NHS tier 2 or tier 3 weight management service. You can also access free tier 1 self-help tools and community programmes directly. Use our free BMI calculator to check your current BMI before your GP appointment — this helps frame the discussion about your health. Waiting times and available services vary by region (integrated care board), so ask your GP about current options in your area.
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.