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
Do Fat Loss Injections Work — And How to Access Them in the UK
Fat loss injections, also called weight loss injections or slimming injections, have become increasingly discussed in the UK health space. Clinical evidence shows that GLP-1 weight loss injections can help people lose weight when combined with lifestyle changes — but they're not a assured solution, and individual results vary significantly. This guide explains how these prescription medications work, whether they're likely to be effective for you, and the two main ways UK adults can access them.
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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.
Who Can Get Fat Loss Injections — UK Eligibility Criteria
To access prescription weight loss injections in the UK, you need to meet specific eligibility thresholds based on BMI and health status. The main criteria are:
- BMI of 30 or above (obesity category), or
- BMI of 27–29.9 (overweight) with at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, abnormal cholesterol, sleep apnoea, or cardiovascular disease history
If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS applies lower BMI thresholds — eligibility may start at BMI 27.5 or above, because these groups face higher type 2 diabetes and heart disease risk at lower weights. You must be at least 18 years old, not pregnant, and not breastfeeding. Your GP or a licensed prescriber will assess your individual circumstances before prescription. Use our free BMI calculator above to check your current BMI instantly and understand which category you fall into.
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.
How to Access Weight Loss Injections — NHS vs Private Routes
There are two main pathways to access weight loss injections in the UK: NHS and private. The NHS route involves asking your GP for a referral to a specialist tier 3 or tier 4 weight management service. Waiting times vary by region — some areas have waits of several months or longer. The private route is faster: you complete an online consultation with a UK-licensed prescriber, and if approved, your prescription is dispensed by a GPhC-registered pharmacy. Private treatment is available without NHS referral but costs between £129–£320 monthly depending on dose. Both routes require a clinical assessment to confirm eligibility and suitability. Try our GLP-1 weight loss calculator to estimate potential outcomes at different doses.
- 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.
How much weight can you realistically lose with fat loss injections?
Clinical trials show average weight loss of 15–21% of body weight over 68–72 weeks with maximum doses, alongside a reduced-calorie diet and increased physical activity. Individual results vary widely — some people lose more, others less. Weight loss typically continues while using the medication and may reverse if you stop without maintaining lifestyle changes.
Are fat loss injections the same as slimming jabs or weight loss jabs?
Yes — "fat loss injections", "slimming jabs", "weight loss jabs", and "slimming injections" all refer to the same category of GLP-1 receptor agonist medications licensed for weight management in the UK. They are prescription-only medicines, not cosmetic injections, and require clinical assessment before prescription.
What's the difference between NHS and private access to weight loss injections?
NHS access requires a GP referral to a specialist weight management service, with potentially long waiting lists. Private access involves an online consultation with a UK-licensed prescriber and is faster — typically days rather than months — but costs between £129–£320 monthly. Both require clinical assessment and a valid prescription.
Do you have to keep taking weight loss injections forever?
No. You and your prescriber can decide when to stop. However, weight loss may reverse if you stop the medication without maintaining the dietary and lifestyle changes that supported the initial loss. Your prescriber will discuss your long-term weight management plan with you.
Can you get fat loss injections on the NHS if you have a BMI under 30?
Yes, if you have a BMI of 27–29.9 and at least one weight-related health condition (such as type 2 diabetes, high blood pressure, or cardiovascular disease). Lower thresholds may apply if you're of South Asian, Black African, Caribbean, or Chinese heritage. Your GP will assess your individual eligibility.
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.