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
Does Stress Cause Weight Loss?
Stress affects people's bodies in different ways. For some, stress can lead to weight loss, whilst others may gain weight. This happens because stress triggers hormonal changes that affect appetite, metabolism, and how your body stores fat. If you're experiencing unintended weight changes alongside stress, it's worth discussing with your GP. For those seeking structured weight management in the UK, prescription options are available for eligible adults, alongside lifestyle support and professional guidance.
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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 Stress Affects Weight in the UK
When you experience stress, your body releases hormones like cortisol and adrenaline. These hormones prepare your body for "fight or flight" and can temporarily suppress appetite, leading to weight loss in the short term. However, prolonged stress often has the opposite effect — many people experience increased appetite and cravings for high-calorie foods.
Stress also affects sleep quality, digestion, and metabolism. Poor sleep combined with stress can slow metabolic rate and increase fat storage, particularly around the abdomen. The relationship between stress and weight is complex and varies significantly between individuals based on genetics, existing health conditions, and how your body responds to stress hormones.
If you're concerned about unintended weight changes or struggling with weight management, your GP can help assess whether stress is a contributing factor and discuss appropriate support options, including weight management in the UK through NHS services or prescription options for eligible adults.
Clinically BackedWeight Loss
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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.
Prescription Weight Management Options Available in the UK
For adults with a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions, prescription weight loss medication is available in the UK. Three main options are licensed: Mounjaro (tirzepatide), a dual GIP/GLP-1 injection; Wegovy (semaglutide), a GLP-1 injection; and Saxenda (liraglutide), a daily injection.
These medications work alongside lifestyle changes — diet, exercise, and stress management — not instead of them. Access is available through NHS weight loss services via referral to specialist tier 3 services, or privately through online prescribing following clinical assessment. Individual eligibility depends on your health profile. Use our free BMI calculator above to check your starting point, and our GLP-1 weight loss calculator to understand potential outcomes if eligible.
- 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.
Can stress alone cause significant weight loss?
Stress can contribute to short-term weight loss through appetite suppression, but significant or prolonged unintended weight loss usually involves multiple factors including medical conditions, medications, or sleep disruption. If you're experiencing unexplained weight loss, discuss it with your GP to rule out underlying health issues.
How does stress-related weight loss differ from intentional weight loss?
Unintended stress-related weight loss often comes with fatigue, sleep problems, and mood changes. Intentional, healthy weight loss through lifestyle changes or prescribed medication typically progresses at 0.5–1 kg per week and is sustainable. Your GP can help distinguish between the two.
What weight loss options are available on the NHS in the UK?
The NHS offers tier 3 specialist weight management services that may include prescription medications like Mounjaro, Wegovy, or Saxenda for eligible adults. Referral from your GP is usually required. Availability varies by region, and waiting lists can be lengthy in some areas.
How do I know if prescription weight loss medication is right for me?
A GP or licensed prescriber assesses your BMI, health conditions, current medications, and medical history. You must have a BMI of 30 or above, or 27–29.9 with weight-related conditions like diabetes or high blood pressure. Individual clinical assessment determines suitability.
What's the difference between stress management and prescription weight loss treatment?
Stress management (therapy, exercise, sleep) addresses root causes of stress-related weight changes. Prescription medication supports weight loss by regulating appetite hormones alongside lifestyle changes. Both approaches are often used together for best results.
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.