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
Medicine That Helps You Lose Weight — Full UK Options
If you're looking for medicine that helps you lose weight in the UK, you have more options than ever. Beyond prescription medications like Mounjaro and Wegovy, weight loss support ranges from free NHS programmes and structured lifestyle changes to specialist medical services. This guide covers every option available, how they work, and how to find the right approach for your situation. Calculate your BMI and explore your personalised weight loss path with our free tools.
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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.
Weight Loss Options in the UK — Full Pathway
Weight loss in the UK follows a structured pathway, starting with self-help and NHS support, then specialist services, then prescription medication if appropriate. Here's what's available:
- Tier 1 (Self-help): Free NHS Weight Loss Plan, digital apps, community weight management groups — no GP referral needed
- Tier 2 (Primary care): GP-led behaviour change programmes, structured exercise classes, dietitian support — available through some GP practices
- Tier 3 (Specialist services): NHS multidisciplinary weight management clinics — where prescription weight loss medication may be offered. Access varies by region and requires GP referral
- Tier 4 (Surgery): Bariatric surgery for severe obesity with significant health complications — available through specialist NHS centres
- Private prescription medicine: Mounjaro (tirzepatide) and Wegovy (semaglutide) available through private online prescribing following clinical assessment — not available on standard NHS prescription but licensed for UK use
Most sustainable weight loss combines medicine with dietary changes and increased physical activity. The NHS recommends losing no more than 0.5–1 kg per week for safe, lasting results.
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 Choose the Right Weight Loss Approach for You
Choosing the right weight loss method depends on your BMI, health conditions, what you've tried before, and what support you need. Start by calculating your BMI using our free BMI calculator — this helps determine eligibility for different support levels. If you have a BMI over 30 or 27 with weight-related health conditions like type 2 diabetes or high blood pressure, you may qualify for specialist services or prescription medication. Consider what works for your lifestyle: some people succeed with structured diet and exercise alone, whilst others benefit from GLP-1 medicine alongside lifestyle changes. Your GP can assess your individual situation, discuss options, and refer you to appropriate services. Many people find that a combination of approaches — such as behaviour change support plus prescription medication — delivers the best sustainable results.
- 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's the safest rate of weight loss?
The NHS recommends losing 0.5–1 kg (1–2 lbs) per week. This pace is sustainable, reduces muscle loss, and helps maintain results long-term. Very gradual weight management over 1.5 kg per week is not recommended without medical supervision and can lead to nutritional deficiencies and muscle loss.
Can I access weight loss medicine on the NHS?
Yes, but availability is limited. Prescription weight loss medication like Mounjaro and Wegovy are available through NHS specialist tier 3 weight management services in some regions, but waiting lists can be long. Your GP can refer you to assess eligibility. Private prescription options are also available through clinical online assessments.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — it activates two hormone pathways. Wegovy (semaglutide) activates only GLP-1. Clinical trials showed Mounjaro may produce slightly higher average weight loss (~20% body weight) compared to Wegovy (~15%), but individual results vary significantly. Both are once-weekly injections requiring prescription and clinical assessment.
Do I need to change my diet if I take weight loss medicine?
Yes. Weight loss medicines are most effective when combined with a reduced-calorie diet and increased physical activity. Medicine alone without lifestyle changes typically produces modest results. Think of medicine as a support tool that makes it easier to follow healthier habits — not a replacement for them.
How do I know if I'm eligible for weight loss support?
Generally, you may be eligible if you have a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Use our free BMI calculator to check your BMI, then speak to your GP about which support pathway is appropriate for your situation.
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.