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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Orlistat Weight Loss: Before and After Results
Orlistat is a prescription weight loss medication available in the UK that works differently from newer GLP-1 injections like Wegovy. Unlike appetite-suppressing injections, orlistat reduces the amount of dietary fat your body absorbs in the digestive system. This guide explains realistic weight loss expectations with orlistat, how long results take to appear, and how it compares to other prescription weight loss options available on the NHS and privately. Individual results vary significantly based on diet, exercise, and adherence.
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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.
How Much Weight Can You Lose With Orlistat?
Clinical evidence shows that orlistat typically helps users lose 2–3 kg more than diet alone over 12 months. This modest but meaningful weight loss usually occurs alongside a reduced-calorie diet and increased physical activity. Some users report losing 5–10 kg over 6–12 months, whilst others see smaller changes. The key factor is consistency: orlistat works best when combined with a calorie deficit of around 500 kcal daily, which typically supports losing approximately 0.5 kg per week.
- Average loss at 6 months: 2–4 kg
- Average loss at 12 months: 3–5 kg alongside lifestyle changes
- Weight loss plateau: Often occurs after 6 months if diet and exercise remain unchanged
- Individual variation: Some users lose up to 10 kg; others see minimal change
Orlistat is not a gradual weight management solution — it works gradually and requires sustained dietary effort. Your GP can assess whether orlistat is suitable for you and monitor your progress using tools like our free BMI calculator to track changes in your health status over time.
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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.
Orlistat vs Other Weight Loss Options
Orlistat is one of several weight management approaches available in the UK. GLP-1 weight loss injections such as Wegovy or Mounjaro are newer alternatives that suppress appetite and typically produce greater average weight loss (15–21% body weight in clinical trials), though they are prescription-only and require clinical assessment. Orlistat is often cheaper and available as a non-prescription option (Xenical XL) or on prescription (Xenical). The NHS weight loss pathway also includes tier 1 self-help programmes, tier 2 behaviour change support, and tier 3 specialist services where prescription medication may be offered.
For realistic comparisons between your current weight and healthy weight targets, try our free weight converter and BMI calculator to understand where you sit on NHS health thresholds. Your GP can discuss which weight management approach suits your individual health needs best.
- 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 long does it take to see weight loss results with orlistat?
Most users begin to see measurable weight loss within 4–8 weeks of starting orlistat, provided they maintain a reduced-calorie diet. Maximum weight loss usually occurs around 6 months. After this point, weight loss often plateaus unless dietary habits change further. Results depend heavily on consistency with diet and exercise rather than the medication alone.
Does orlistat give clinically studied weight loss results?
No. Orlistat helps reduce dietary fat absorption but does not clinically studied weight loss. Studies show orlistat users lose an average of 2–3 kg more than diet alone, but individual results vary significantly. Without dietary changes, orlistat has minimal effect. It works best as part of a comprehensive weight management plan including calorie reduction and physical activity.
Can I compare orlistat results to GLP-1 weight loss injections?
GLP-1 medications like Wegovy show greater average weight loss (approximately 15% body weight) in clinical trials compared to orlistat (typically 3–5 kg). However, both require prescription and clinical assessment. GLP-1 injections suppress appetite, whilst orlistat reduces fat absorption. Your GP can discuss which option suits your health profile and NHS eligibility.
What are realistic before-and-after timelines with orlistat?
Weeks 1–4: no visible change; weeks 4–8: first measurable weight loss appears; 12 weeks: noticeable difference for many users; 6 months: maximum average loss achieved. Weight loss then plateaus unless lifestyle changes are sustained. Progress varies greatly — use our free progress tracker to monitor your individual journey month by month.
Why is orlistat weight loss smaller than GLP-1 injections?
Orlistat works locally in the digestive system, preventing fat absorption. GLP-1 injections act on brain appetite centres, reducing hunger and food intake. GLP-1 medications therefore typically produce larger average weight losses. Orlistat is useful for users who prefer non-injectable options or have different health needs — your GP can advise which suits your situation best.
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.