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 Worry Cause Weight Loss?
Yes, worry and prolonged stress can cause weight loss in some people, though the effect varies significantly. When you're anxious or stressed, your body releases cortisol and adrenaline, which can suppress appetite and increase metabolism. However, this isn't a safe or sustainable approach to weight management. If you've noticed unexplained weight loss linked to worry or anxiety, it's worth discussing with your GP. For intentional weight management in the UK, evidence-based approaches—including lifestyle changes and, where appropriate, prescription weight loss medications—are far more reliable and healthier options.
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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 and Worry Affect Body Weight
Worry triggers your body's "fight or flight" response, releasing hormones like cortisol and adrenaline. These chemicals can temporarily suppress appetite and increase your metabolic rate, leading to weight loss in some people. However, this effect is usually short-term and varies widely between individuals. Some people actually experience the opposite—stress-related emotional eating and weight gain—especially during chronic or prolonged anxiety.
- Acute stress (short-term worry): May reduce appetite for hours or days
- Chronic stress (ongoing anxiety): Can lead to unpredictable eating patterns and metabolic changes
- Individual variation: Genetics, personality, and coping mechanisms all influence how stress affects weight
Weight loss caused by worry is not healthy or sustainable. Unintentional weight loss linked to anxiety should always be evaluated by your GP, as it can indicate an underlying health issue. For intentional weight management in the UK, prescription weight loss medications like Mounjaro and Wegovy—combined with lifestyle changes—offer evidence-based support alongside structured dietary and physical activity approaches.
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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.
When to Seek GP Advice
If you've noticed unintentional weight loss alongside worry or anxiety, contact your GP. Unexplained weight changes can signal various health conditions, including thyroid problems, depression, or other medical issues. Your GP can assess your symptoms, run necessary tests, and refer you to appropriate support—such as talking therapies for anxiety or weight management services.
For intentional, sustainable weight management, the NHS offers a structured pathway. Many adults benefit from combining lifestyle changes with professional support. Use our free BMI calculator above to check your current weight status, and discuss your goals with your GP. If eligible, you may be referred to NHS weight management services or assessed for prescription options like GLP-1 weight loss injections, which have shown effectiveness in UK clinical practice alongside reduced-calorie diets and increased physical activity.
- 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?
Short-term stress can suppress appetite and increase metabolism, leading to modest weight loss. However, prolonged stress affects individuals differently—some lose weight, others gain it through emotional eating. Significant unintentional weight loss should always be evaluated by your GP to rule out underlying health conditions.
Is weight loss from worry the same as healthy weight loss?
No. Weight loss caused by stress or worry is often uncontrolled and may indicate your body is under strain. Healthy, sustainable weight loss involves a modest calorie deficit (around 500 kcal/day) combined with balanced nutrition and physical activity. It should ideally be monitored and supported by a healthcare professional.
What should I do if I'm losing weight due to anxiety?
Contact your GP. Unintentional weight loss linked to anxiety requires professional assessment. Your GP can rule out medical causes, evaluate your mental health, and refer you to appropriate support—such as cognitive behavioural therapy (CBT) or counselling for anxiety management.
Are there evidence-based weight management options in the UK?
Yes. The NHS offers tiered weight management support, starting with lifestyle changes and progressing to specialist services. Prescription weight loss medications like Mounjaro (tirzepatide) and Wegovy (semaglutide) are available for eligible adults through NHS or private prescribing, following clinical assessment alongside dietary and activity changes.
How can I check if my current weight is healthy?
Use our free BMI calculator on this page to find your BMI, which the NHS uses as a screening tool for healthy weight ranges. A healthy BMI is 18.5–24.9 for most adults (lower thresholds apply for South Asian and Black African heritage). Your GP can provide personalised advice based on your individual health profile.
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.