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
Safe Weight Loss Products in the UK
Finding safe weight loss products can be overwhelming, but evidence-based options are available through the NHS and private prescribing in the UK. Safe weight management combines lifestyle changes with, where appropriate, prescription medications that have been clinically tested and approved by UK regulators. Understanding which products work, how they function, and whether they're right for you requires accurate information. This guide covers prescription weight loss options, their mechanisms, and how to access them safely through a clinical assessment with your GP or a licensed prescriber.
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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.
Prescription Weight Loss Medications Available in the UK
Three prescription-only weight loss medications are currently licensed in the UK for adult weight management, all requiring a clinical assessment before prescription:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist injected once weekly. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity.
- Wegovy (semaglutide) — a GLP-1 receptor agonist injected once weekly. In the STEP-1 clinical trial, participants achieved an average weight loss of approximately 14.9% of body weight at 68 weeks.
- Saxenda (liraglutide) — a GLP-1 receptor agonist given as a daily injection. Evidence supports modest weight loss, typically 5–10% of body weight.
All three work by helping regulate appetite and food intake. Individual results vary significantly — weight loss depends on adherence, diet, exercise, and personal metabolism. These medications are prescribed only where clinical assessment confirms they're appropriate for your health status.
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 Weight Loss Without Medication
The NHS recommends lifestyle-based weight management as the first-line approach for sustainable weight loss. Safe, evidence-based methods include:
- Calorie deficit of 500 kcal per day (typically results in ~0.5 kg loss per week)
- Mediterranean or low-calorie balanced diet
- 150 minutes of moderate aerobic activity weekly plus strength training
- Behavioural support through NHS Tier 1 or Tier 2 weight management services
- Sleep improvement and stress management
Even a 5–10% reduction in body weight brings meaningful health benefits, including lower blood pressure, improved blood sugar control, and reduced joint strain. Use our free BMI calculator to establish your current weight status, and try our progress tracker to monitor sustainable changes 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.
What makes a weight loss product "safe" in the UK?
Safe products have been evaluated by the MHRA (Medicines and Healthcare products Regulatory Agency), have evidence from clinical trials, clearly state risks and side effects, and require appropriate medical assessment before use. Prescription medications are safer than unregulated supplements because they're quality-assured and monitored for safety.
Can I get prescription weight loss medication on the NHS?
Yes, if you meet eligibility criteria (typically BMI ≥30 or ≥27.5 with weight-related health conditions). Access is through NHS specialist tier 3 weight management services via your GP referral. Waiting times vary significantly by region. Private online prescribing is an alternative route if NHS access is limited in your area.
Are weight loss injections safe for long-term use?
Mounjaro and Wegovy have been used in clinical trials for 68–72 weeks with safety monitoring. Longer-term safety data is still being gathered. These medications are subject to additional MHRA monitoring (Black Triangle status). Your prescriber will assess ongoing safety through regular reviews and blood work where appropriate.
How much weight will I lose with prescription medication?
Clinical trials show average weight losses of 15–21% of body weight, but individual results vary considerably. Some people lose 5–10%, others lose 25%+. Weight loss depends on dose, adherence, diet, exercise, genetics, and metabolism. Calculate your potential range using our free GLP-1 weight loss calculator, but remember results are not assured.
What's the safest weight loss rate?
The NHS recommends losing 0.5–1 kg per week for sustainable, safe weight loss. Faster loss increases risks of muscle loss, nutritional deficiencies, and metabolic adaptation. Use our free progress tracker to monitor your weight at a safe, steady pace alongside a balanced diet and regular physical activity.
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.