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
Cortisol and Weight Loss — What UK Adults Need to Know
Cortisol is a natural hormone that affects appetite, fat storage, and metabolism. While cortisol management is important for overall health, the most effective evidence-based approach to weight management in the UK involves prescription medications alongside lifestyle changes. If you're struggling with weight and have a BMI of 30 or above (or 27 with weight-related health conditions), you may be eligible for prescription weight loss treatment through the NHS or privately. This guide explains your options.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
UK-Licensed Prescription Weight Loss Medications
Three prescription medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are GLP-1 receptor agonist medications (Mounjaro is a dual GIP/GLP-1 agonist) that help regulate appetite and support feeling fuller after meals.
- Mounjaro: Once-weekly injection, doses from 2.5 mg to 15 mg. Clinical trials showed average weight loss of 15–21% of body weight alongside a reduced-calorie diet and increased physical activity.
- Wegovy: Once-weekly injection, doses up to 2.4 mg. STEP clinical trials demonstrated average weight loss of approximately 15% of body weight.
- Saxenda: Daily injection, doses up to 3 mg. Available for longer than Mounjaro and Wegovy.
All three medications require a prescription and clinical assessment to determine eligibility. Individual results vary significantly, and weight loss is most effective when combined with dietary changes and regular exercise.
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 Prescribing in the UK
Weight loss medication is available through two pathways in the UK. NHS access: Specialist tier 3 weight management services can prescribe these medications, but availability varies significantly by region and waiting lists can be lengthy. Your GP can refer you if you meet eligibility criteria. Private access: Available through GPhC-registered online prescribers following an online clinical assessment, without NHS referral. Costs typically range from £129–£320 per month depending on dose and provider.
To find out if you're eligible, calculate your BMI using our free BMI calculator above, then contact your GP to discuss weight management options. Your GP can assess your individual health needs and explain both NHS and private pathways available to you.
- 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.
Does cortisol directly cause weight gain?
Cortisol affects appetite, metabolism, and where the body stores fat, but weight gain is multifactorial. Cortisol management through stress reduction, sleep, and exercise is important for overall health. However, for significant weight management, evidence-based approaches like prescription medication (if eligible), calorie deficit, and increased physical activity are most effective. Your GP can assess your individual situation.
What weight loss results can I expect with prescription medication?
Clinical trials show average weight loss of 15–21% of body weight with Mounjaro and approximately 15% with Wegovy over 12–18 months, alongside a reduced-calorie diet and exercise. However, individual results vary significantly — some people lose more, others less. Results depend on adherence, lifestyle changes, and individual metabolism. A prescriber will discuss realistic expectations for you personally.
Am I eligible for weight loss medication on the NHS?
NHS prescribing is typically available through specialist tier 3 weight management services for adults with a BMI of 30 or above, or 27 or above with weight-related health conditions (such as type 2 diabetes, high blood pressure, or sleep apnoea). South Asian, Chinese, Black African, and Black Caribbean adults may qualify at lower BMI thresholds. Ask your GP about referral to your local specialist service.
Can I get weight loss medication privately without waiting for the NHS?
Yes. Private prescriptions are available through UK-licensed online prescribers following a clinical assessment. You don't need an NHS referral. Medications are dispensed by GPhC-registered pharmacies. Costs vary by dose and provider. All prescription medications still require an assessment to confirm they're appropriate for your health.
How should I track my progress with weight loss medication?
Regular weigh-ins, body measurements, and how clothes fit are useful indicators. Our free progress tracker on this page helps you log weight loss over time. Alongside medication, track dietary changes, physical activity levels, and how you feel (energy, mood, sleep). Discuss progress with your prescriber at regular check-ins — they may adjust your dose based on results and any side effects.
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.