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
What to Do When You Hit a Weight Loss Plateau
A weight loss plateau is frustrating but completely normal — it happens when your body adapts to your current diet and activity level. If you've been losing weight steadily and progress has slowed, you're not alone. The good news is that several approaches can help, including lifestyle adjustments and, for eligible adults, prescription weight management medication available through the NHS or privately in the UK. Understanding your options is the first step to breaking through.
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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.
Prescription Weight Loss Options Available in the UK
Three main prescription weight loss medications are licensed in the UK for adults struggling with weight management:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist administered once weekly, available from 2.5mg to 15mg. Clinical trials showed participants lost an average of 15–21% of body weight alongside a reduced-calorie diet and increased physical activity.
- Wegovy (semaglutide) — a GLP-1 receptor agonist given once weekly, with a maximum dose of 2.4mg. Evidence from the STEP trials demonstrated average weight loss of approximately 15% over 68 weeks.
- Saxenda (liraglutide) — a daily GLP-1 injection option, with doses from 0.6mg to 3mg daily.
All three are prescription-only medicines and require assessment by a licensed prescriber to determine eligibility and suitability. They work best when combined with dietary changes and physical activity — they are not a substitute for lifestyle modification but can support your efforts when a plateau occurs.
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.
NHS Access vs Private Options — What You Need to Know
Through the NHS: Weight loss medications are available via tier 3 specialist weight management services. You'll need a referral from your GP, though access and waiting times vary significantly across UK regions. Not all areas have equal availability.
Privately: Prescription weight loss medications are accessible through GPhC-registered online pharmacies following an online clinical assessment. No NHS referral is needed, though costs typically range from £129–£320 per month depending on dose and provider. To find out if you're eligible, speak with your GP about your weight loss plateau — they can discuss both NHS and private options. A prescriber will assess your BMI, health history, and any weight-related conditions to determine suitability.
- 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.
Why do weight loss plateaus happen?
Plateaus occur when your body adapts to your current calorie intake and activity level. Your metabolic rate drops as you lose weight, requiring further calorie reduction or increased exercise to continue losing. It's a normal physiological response and doesn't mean your efforts have failed.
Are prescription weight loss injections suitable for a plateau?
Prescription medications like Mounjaro and Wegovy may help if you meet NHS eligibility criteria: BMI of 30 or above, or 27–29.9 with weight-related health conditions. A GP or licensed prescriber assesses individual suitability. Results vary significantly between individuals.
How quickly can I expect results with prescription weight loss medication?
Clinical trials show weight loss over weeks to months, but individual timelines vary. Mounjaro and Wegovy require gradual dose escalation (weeks 1–20+), and results depend on adherence, diet, and physical activity. Some people see results within 4–8 weeks; others take longer.
Can I use weight loss medication on the NHS if I hit a plateau?
Potentially, if you meet eligibility criteria and are referred to a tier 3 specialist weight management service. However, NHS access varies by region and waiting lists can be lengthy. Your GP can advise whether you're eligible and discuss available pathways in your area.
What should I do alongside prescription medication to break a plateau?
Prescription medications work best alongside lifestyle changes: maintain a modest calorie deficit (around 500 kcal daily for 0.5kg weekly loss), increase physical activity, prioritise sleep, and manage stress. Use our free progress tracker to monitor weight trends and our BMI calculator to track health metrics. Consistency matters more than rapid progress.
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.