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
Do Cortisol Supplements Really Help With Weight Loss?
Cortisol supplements are marketed for weight loss, but evidence supporting their effectiveness is limited. While stress management is important for overall health, prescription weight management options may be more effective for eligible adults in the UK. If you're looking to lose weight, it's worth understanding both supplement claims and clinically-proven alternatives available through your GP or licensed healthcare providers.
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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.
UK-Licensed Prescription Weight Loss Options
If you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure, you may be eligible for prescription weight loss medication in the UK. The most commonly prescribed options are:
- Mounjaro (tirzepatide) — a once-weekly dual GIP and GLP-1 injection. Clinical trials showed it helped participants lose an average of 15–21% body weight.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection with average weight loss of around 15% of body weight in trials.
- Saxenda (liraglutide) — a daily GLP-1 injection, also available for weight management in the UK.
These medications work by helping regulate appetite and support feeling fuller after meals. Weight loss is typically achieved alongside a reduced-calorie diet and increased physical activity. Results vary significantly between individuals.
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.
Getting Started: NHS vs Private Routes
NHS access: Speak to your GP about being referred to a specialist weight management service (tier 3). Availability and waiting times vary by region, but services offer multi-disciplinary support including nutrition and behaviour change guidance.
Private access: UK-licensed prescribers offer online consultations followed by prescription if clinically appropriate. This route typically has shorter timescales but involves private costs.
Whichever route you choose, a healthcare professional will assess whether prescription medication is suitable for you personally. Use our free BMI calculator above to check your current BMI and understand your eligibility threshold.
- 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.
Do cortisol-lowering supplements actually help you lose weight?
Limited scientific evidence supports cortisol supplements for weight loss. While chronic stress may affect metabolism, supplement claims are not well-supported by clinical trials. Stress management, sleep, and diet are important, but prescription medication has stronger clinical evidence for weight loss outcomes.
What's the difference between cortisol supplements and prescription weight loss injections?
Cortisol supplements are nutritional products with weak evidence. Prescription weight loss medications like Mounjaro and Wegovy are clinically-tested medicines that work via hormone pathways (GLP-1 and GIP) and have demonstrated weight loss in large-scale trials. They require prescription and clinical assessment.
Can I get weight loss medication on the NHS in the UK?
Yes. If your BMI is 30 or above (or 27+ with weight-related conditions), ask your GP about referral to a specialist weight management service. NHS services vary by region — some have waiting lists, others offer rapid access. Availability depends on your local integrated care board.
How much weight can I expect to lose with prescription medication?
On average, Mounjaro users lost 15–21% body weight and Wegovy users lost around 15% in clinical trials — but individual results vary significantly. Some people lose more, some less. Weight loss depends on the dose, your adherence, dietary changes, and physical activity levels.
Is it worth trying cortisol supplements before asking my GP about prescription options?
If you're struggling with weight management, it's worth having a conversation with your GP now rather than trying unproven supplements first. Your GP can assess whether prescription medication is appropriate for you, discuss NHS or private options, and provide ongoing support and monitoring.
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.