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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Diet Gel Weight Loss: UK Prescription Medication Options
"Diet gel" weight loss refers to prescription weight management injections available in the UK. These are GLP-1 and GIP receptor agonist medications that may help regulate appetite and support sustainable weight loss alongside dietary changes. If you're interested in weight management options in the UK, you may be eligible for prescription medication through either NHS specialist services or private prescribing. This guide explains how these medications work, who can access them, and what to expect from the process.
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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.
UK-Licensed Weight Loss Medications and Eligibility
The main prescription weight loss medications available in the UK are Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All are GLP-1 or dual GIP/GLP-1 receptor agonist injections that may help with weight management when used alongside a reduced-calorie diet and increased physical activity.
- Mounjaro: Once-weekly injection. Dual GIP and GLP-1 agonist. In clinical trials, users lost an average of 15–21% of body weight over 72 weeks.
- Wegovy: Once-weekly injection. GLP-1 agonist only. Clinical trials showed average weight loss of approximately 15% of body weight.
- Saxenda: Daily injection. GLP-1 agonist. Older option, requires more frequent injections.
You may be eligible if you have a BMI of 30 or above, or BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds apply. Use our free BMI calculator above to check your personal BMI instantly.
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.
NHS vs Private Access and How to Get Started
NHS access: Prescription weight loss medication is available through specialist tier 3 weight management services, but availability varies significantly by region and waiting lists can be lengthy. Your GP can refer you to your local specialist service for assessment.
Private access: UK-licensed prescribers offer online consultations for weight loss medication assessment, with faster access and no waiting lists. A clinical assessment determines suitability based on your individual health.
To find out if you're eligible, speak to your GP about NHS options or arrange a private consultation with a UK-licensed prescriber. Both pathways require a prescription and clinical assessment — these medications are not available over the counter. Track your weight management progress with our free progress tracker once you've started treatment.
- 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 diet gel weight loss medication?
"Diet gel" weight loss refers to prescription injectable medications containing GLP-1 or GIP receptor agonists. These drugs mimic natural hormones that help regulate appetite and blood sugar. In the UK, the main options are Mounjaro, Wegovy, and Saxenda — all prescription-only medicines requiring clinical assessment.
Can I get weight loss injections on the NHS in the UK?
Yes. Weight loss medications are available through NHS specialist tier 3 weight management services if you meet eligibility criteria (typically BMI ≥30 or BMI 27–29.9 with weight-related conditions). Access varies by region and waiting times can be several months. Ask your GP about referral to your local service.
How much weight can I lose with prescription weight loss medication?
Clinical trials show average weight loss of 15–21% of body weight over several months, depending on the medication and dose. Individual results vary significantly and depend on diet, physical activity, and personal factors. Use our GLP-1 weight loss calculator to see projected outcomes at different doses.
Are weight loss injections available privately in the UK?
Yes. UK-licensed prescribers offer online consultations and can issue prescriptions if clinically appropriate. Private options typically have shorter waiting times than NHS services but involve a cost. Prescriptions are dispensed by GPhC-registered pharmacies.
What are the side effects of weight loss injections?
Common side effects include nausea, diarrhoea, constipation, and stomach discomfort — particularly when starting or increasing doses. Most side effects are mild and decrease over time. Serious side effects are rare but can include severe stomach pain or allergic reactions. Always report concerns to your prescriber.
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.