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
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Best Machine For Weight Loss — What Really Works
When people search for the "best machine for weight loss," they're often looking for a structured approach — but the most effective weight management solutions in the UK involve a combination of approaches. There's no single machine or device that assures weight loss on its own. Instead, the evidence supports prescription weight loss medication alongside dietary changes, physical activity, and behavioural support. This guide explains what actually works for weight management in the UK, including prescription options like GLP-1 injections, NHS support pathways, and how to assess what might be right for your situation.
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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.
How Weight Loss Actually Works — The Science
Weight loss happens when you create a calorie deficit — burning more energy than you consume. The NHS recommends losing weight at a rate of 0.5 to 1 kg per week for sustainable results. This typically requires a deficit of around 500 kcal per day, achieved through dietary changes and increased physical activity. Prescription weight loss medications like GLP-1 injections (Wegovy and Mounjaro) work by helping regulate appetite and support feeling fuller after smaller meals, making it easier to maintain a calorie deficit alongside lifestyle changes. Clinical trials show that Wegovy (semaglutide) helped participants lose an average of approximately 15% of body weight — though individual results vary significantly and depend on adherence to diet, exercise, and the medication itself. These medications are prescription-only and require a clinical assessment before being prescribed, typically through NHS specialist services or private prescribing pathways.
- 500 kcal daily deficit = approximately 0.5 kg weight loss per week
- GLP-1 medications support appetite regulation and portion control
- Results depend on combining medication with lifestyle changes
- Individual outcomes vary based on starting weight, metabolism, and adherence
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.
Prescription Weight Loss Options Available in the UK
The UK has three prescription-only weight management injections licensed for weight loss: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Mounjaro is a dual GIP and GLP-1 receptor agonist that may support weight loss through appetite regulation; Wegovy is a once-weekly GLP-1 injection; Saxenda is a daily injection. Access varies depending on your route — NHS weight loss medication is prescribed through specialist tier 3 services (referral from your GP required), whilst private options are available through online clinical assessments with UK-licensed prescribers. All require a prescription and are assessed individually. Use our free BMI calculator to check your BMI, and our GLP-1 weight loss calculator can help you estimate potential weight loss at different doses. Your GP can advise on NHS eligibility based on your BMI 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 there a machine that can help me lose weight without diet or exercise?
No single machine assures weight loss without lifestyle changes. Prescription GLP-1 medications (Wegovy, Mounjaro) work by supporting appetite control, but they're most effective alongside reduced-calorie diet and increased physical activity. Weight loss requires creating a calorie deficit — medication helps make that easier, not replace it entirely.
What is Wegovy and how does it work for weight loss?
Wegovy (semaglutide) is a prescription-only once-weekly injection that activates the GLP-1 hormone pathway, helping reduce appetite and food cravings. In clinical trials, it helped participants lose an average of approximately 15% of body weight over 68 weeks alongside diet and exercise. Individual results vary, and it requires a prescription following clinical assessment.
How can I access prescription weight loss medication on the NHS?
Ask your GP for a referral to your local specialist weight management service (tier 3). Eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure. Waiting times and availability vary by region. Private options are also available through online prescribing.
How much weight can I expect to lose with prescription weight loss medication?
Clinical trial data shows average weight loss of 15–21% of body weight with GLP-1 medications, but individual results vary significantly. Some people lose more, others less — it depends on adherence to diet and exercise, starting weight, metabolism, and the medication dose. Your prescriber will discuss realistic expectations for your situation.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) is a GLP-1-only agonist. Mounjaro showed average weight loss of 15–21% in trials; Wegovy approximately 15%. Both are once-weekly injections. Your prescriber will assess which is more appropriate based on your health profile and preferences.
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.