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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Saxenda Weight Loss Pen — What You Need to Know
Saxenda is a prescription-only weight loss injection licensed in the UK for adults with obesity or overweight with weight-related health conditions. It contains liraglutide, a GLP-1 receptor agonist that may help reduce appetite and support sustainable weight management alongside lifestyle changes. Unlike some newer weight loss injections, Saxenda is a once-daily pen injection rather than weekly. This guide covers how Saxenda works, UK eligibility, dosing, and what the evidence shows about expected weight loss outcomes.
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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 Saxenda Works and What to Expect
Saxenda (liraglutide) is a GLP-1 receptor agonist — it mimics a natural hormone your gut produces after eating. It works by signalling to your brain that you're full, reducing appetite and cravings, and slowing how quickly food leaves your stomach. This may help you eat smaller portions and feel satisfied with less food.
In clinical trials, adults using Saxenda alongside a reduced-calorie diet and increased physical activity lost an average of 5–10% of their body weight, though individual results vary significantly. Some people achieve greater weight loss; others see more modest results. Weight loss typically develops gradually over weeks and months of consistent use.
- Reduces appetite and food cravings
- Helps you feel fuller after smaller meals
- Works best alongside dietary and lifestyle changes
- Results take time — not a quick-fix solution
Saxenda requires a prescription from a UK-licensed prescriber and a clinical assessment to confirm it's suitable for your health.
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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.
Saxenda Dosing, Side Effects, and Access in the UK
Dosing: Saxenda starts at 0.6 mg once daily and increases gradually over 4 weeks to a maximum of 3 mg once daily. Each dose is injected under the skin (subcutaneously) — typically in the stomach, thigh, or upper arm.
Common side effects include nausea, diarrhoea, constipation, and stomach pain — these often improve as your body adjusts. More serious side effects are rare but can include pancreatitis or gallbladder problems. Always report severe abdominal pain to your GP immediately.
Access in the UK: Saxenda is available through NHS specialist weight management services (tier 3) with a GP referral, though availability and waiting times vary by region. It's also available privately through GPhC-registered online prescribing services following a clinical assessment. Use our free GLP-1 weight loss calculator to explore potential outcomes, and check your BMI using our free BMI calculator to understand your current health context.
- 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 is Saxenda different from Wegovy or Mounjaro?
Saxenda (liraglutide) is a once-daily injection; Wegovy (semaglutide) is once-weekly; Mounjaro (tirzepatide) is also once-weekly but uses a dual GIP+GLP-1 mechanism rather than GLP-1 alone. Clinical trial data shows average weight loss of 5–10% for Saxenda, ~15% for Wegovy, and ~15–21% for Mounjaro — though individual results vary. Your prescriber can advise which is suitable for you.
Can I get Saxenda on the NHS?
Yes, Saxenda is available through NHS specialist weight management services (tier 3). You'll need a GP referral and assessment. However, availability, eligibility criteria, and waiting times vary significantly by region and local commissioning. Contact your GP to ask about your local services. Private access is also available through online prescribing.
How long does Saxenda take to work?
Weight loss typically begins within a few weeks but develops gradually over months. Most weight loss occurs between weeks 4–12 as your dose increases. Saxenda works best when combined with a reduced-calorie diet and increased physical activity — it's not a standalone solution.
What happens if I stop taking Saxenda?
If you stop Saxenda, appetite and food intake typically return to baseline over time, and weight loss may plateau or reverse. Saxenda is intended for ongoing use as part of a long-term weight management approach. Your prescriber will advise on duration and whether continuation is appropriate for your health.
Is Saxenda safe for people with type 2 diabetes?
Saxenda can be used in people with type 2 diabetes, but your prescriber must assess your individual situation carefully. If you take diabetes medications like insulin or sulphonylureas, your doses may need adjustment — always inform your prescriber of all medications and conditions.
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.