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
Weight Loss Shots — Options Available in the UK
Weight loss shots, also called slimming injections or weight loss injections, are prescription-only medications that can support weight management when combined with lifestyle changes. In the UK, several options are available through NHS specialist services and private prescribing. This guide covers the different approaches to weight loss—from free NHS support through to prescription medications—to help you understand what's right for your situation.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Understanding Your Weight Loss Options
Weight loss in the UK context involves a structured pathway from self-help to specialist care. The NHS offers a tiered approach: tier 1 includes free digital tools and community programmes; tier 2 provides GP-led behaviour change support; tier 3 is specialist multidisciplinary weight management services where prescription medications may be considered; and tier 4 offers bariatric surgery for severe obesity. Prescription weight loss shots available in the UK include Mounjaro (tirzepatide), a dual GIP and GLP-1 receptor agonist, and Wegovy (semaglutide), a GLP-1 injection—both once-weekly prescription-only medicines. Clinical trials show these medications may help adults lose an average of 15–21% of body weight alongside a reduced-calorie diet and increased physical activity, though individual results vary. Eligibility typically requires a BMI of 30 or above, or 27 with weight-related health conditions such as type 2 diabetes or high blood pressure. Our GLP-1 weight loss calculator can help you estimate potential weight loss outcomes at different dose levels, giving you realistic expectations for discussion with your prescriber.
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.
Choosing the Right Approach for You
The best weight loss method depends on your BMI, health conditions, lifestyle, and personal preferences. Start by calculating your BMI using our free BMI calculator to understand where you fall on NHS guidelines—a healthy BMI is 18.5–24.9 for most adults, or 18.5–22.9 for those of South Asian, Black African, or Caribbean heritage. If you're overweight or obese, speak to your GP about nhs weight loss programme options available in your area. Many regions offer free digital programmes and group support. If these haven't worked or you have weight-related health conditions, ask about referral to tier 3 specialist services, where prescription weight loss injections may be discussed. For lose weight safely with medication, ensure any prescriber assesses your individual eligibility and monitors your progress. Track your journey using our free progress tracker to stay motivated and accountable throughout your weight loss.
- 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 are weight loss shots and how do they work?
Weight loss shots are prescription-only injectable medications (Mounjaro or Wegovy in the UK) that activate natural hormones to reduce appetite and help you feel fuller. They're used alongside diet and exercise for sustainable weight loss. Both are once-weekly injections available through NHS specialist services or private prescribing.
Are weight loss injections available on the NHS?
Yes, Mounjaro and Wegovy are approved by NICE for NHS specialist weight management services (tier 3). However, NHS availability varies significantly by region and waiting times can be lengthy. Private prescribing routes are also available through UK-licensed online prescribers.
Who is eligible for weight loss shots in the UK?
Adults with a BMI of 30 or above, or 27+ with weight-related health conditions (diabetes, high blood pressure, sleep apnoea), may be eligible. Eligibility is assessed individually by a prescriber based on medical history. Lower BMI thresholds apply for people of South Asian or Black heritage.
What results can I expect from weight loss shots?
Clinical trials show average weight loss of 15–21% of body weight over 68–72 weeks, alongside reduced-calorie diet and exercise. Individual results vary significantly—some people lose more, others less. Weight loss typically begins within weeks and continues over several months.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) activates two hormone pathways (GIP and GLP-1) with higher average weight loss (15–21%), while Wegovy (semaglutide) activates one pathway (GLP-1 only) with average loss around 15%. Both are once-weekly injections. Your prescriber will assess which suits you based on your health profile.
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.