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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Wegovy 2.5mg Starting Dose — UK Health Guide
Wegovy 2.5mg is the initial starting dose for semaglutide weight management in the UK. It's a prescription-only weekly injection that activates your body's natural GLP-1 hormone pathway to help regulate appetite and support feeling fuller after meals. This guide explains how the starting dose works, what to expect, and how it fits into your weight management journey alongside lifestyle changes. According to NHS guidance, weight loss medications are typically used with a reduced-calorie diet and increased physical activity for best results.
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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.
How Wegovy 2.5mg Works and Dosing Schedule
Wegovy (semaglutide) 2.5mg is the lowest starting dose used to allow your body to adjust to the medication. You'll receive this dose for your first 4 weeks of treatment as a once-weekly injection. After 4 weeks, if tolerated well, your prescriber will typically increase your dose to 0.5mg, then progress to 1mg, 1.7mg, and finally 2.4mg (the maximum maintenance dose). The 2.5mg dose works by stimulating GLP-1 receptors in your brain and gut, which may help reduce appetite, support blood sugar regulation, and slow how quickly food leaves your stomach. Clinical trials (STEP-1) showed that semaglutide at maintenance doses helped participants lose an average of approximately 15% of their body weight — though individual results vary significantly. Use our free GLP-1 weight loss calculator above to see what potential results might look like at different doses based on your current weight.
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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.
What to Expect When Starting Wegovy 2.5mg
The most common side effects at the starting dose are nausea, diarrhoea, constipation, and stomach discomfort — these typically ease over the first few weeks as your body adjusts. Many people experience reduced appetite, which is expected. You'll give yourself a once-weekly injection under the skin, usually in your stomach, thigh, or upper arm. It's important to combine this with a reduced-calorie diet and regular physical activity — the medication is a tool to support these lifestyle changes, not a replacement for them. Your prescriber will monitor your progress and tolerability at each dose before increasing. If you experience severe stomach pain, persistent vomiting, or signs of allergic reaction, contact your GP immediately.
- 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.
Is Wegovy 2.5mg the same as Ozempic 2.5mg?
No. Although both contain semaglutide, Wegovy is specifically licensed for weight management in the UK, while Ozempic is licensed for type 2 diabetes (up to 2mg dose). Wegovy goes up to 2.4mg and is the correct prescription for weight loss — Ozempic is not licensed for weight loss in the UK.
How long do you stay on the 2.5mg dose of Wegovy?
You'll remain on 2.5mg for your first 4 weeks only. After that, your prescriber will typically increase your dose weekly if tolerated well, moving through 0.5mg, 1mg, 1.7mg, and up to 2.4mg maintenance dose.
Can I get Wegovy 2.5mg on the NHS in the UK?
Wegovy access on the NHS is limited and varies by region. You'd typically need a referral to a specialist tier 3 weight management service. Private prescriptions through online GPs are more readily available but require payment.
What's the difference between Wegovy and Mounjaro doses?
Wegovy starts at 0.25mg, whereas Mounjaro starts at 2.5mg. Mounjaro is a dual GIP/GLP-1 agonist (different mechanism), so doses aren't directly comparable. Clinical trial data suggests both support weight loss, but individual results vary.
How can I track my weight loss progress on Wegovy?
Use our free progress tracker on this page to log your weight weekly and visualise your results over time. Also use the BMI calculator to monitor changes in your BMI alongside your weight, and the weight converter to switch between kg and stone for NHS context.
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.