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
Can You Lose Weight Without Working Out?
Yes, you can lose weight without exercise — weight loss is primarily driven by creating a calorie deficit through diet. However, combining dietary changes with physical activity produces better long-term results and greater health benefits. In the UK, weight management can involve lifestyle changes alone, prescription medications like GLP-1 injections, or both together. This guide explains what works, what the evidence shows, and your options through the NHS or private prescribing. Your GP can help you choose the right approach for your health goals.
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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 Weight Loss Works Without Exercise
Weight loss happens when you consume fewer calories than your body burns — this is called a calorie deficit. You don't need to exercise to create this deficit; dietary changes alone can achieve meaningful weight loss. The NHS recommends losing 0.5 to 1 kg per week for sustainable results, which typically requires a daily deficit of around 500 calories.
- A reduced-calorie diet can result in weight loss without any increase in physical activity
- Portion control, eating more whole foods, and reducing ultra-processed items are key strategies
- Crash diets and very low-calorie diets (under 800 kcal/day) should only be attempted under medical supervision
- The rate of weight loss varies based on starting weight, age, metabolism, and other factors
However, exercise offers additional benefits beyond calorie burn: it preserves muscle during weight loss, improves cardiovascular health, and supports long-term weight maintenance. For NHS weight management, prescription weight loss medication combined with dietary changes can help when lifestyle modification alone hasn't worked.
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.
Weight Loss Medication — An Option Without Exercise Focus
If diet alone hasn't produced results, GLP-1 weight loss injections are prescription-only medications available in the UK that can help. These include Wegovy (semaglutide) and Mounjaro (tirzepatide), licensed specifically for weight management in UK adults with a BMI of 30 or above, or 27 or above with weight-related health conditions like type 2 diabetes or high blood pressure.
Clinical trials show Wegovy helped people lose an average of around 15% of body weight over 68 weeks — individual results vary significantly. These medications work by reducing appetite and helping you feel fuller after smaller meals, making it easier to maintain a calorie deficit through diet alone. Access in the UK is through NHS specialist services (which may have waiting lists) or private prescribing following a clinical assessment. A prescriber will assess whether this medication is suitable for you based on your individual health.
Try our free GLP-1 weight loss calculator to explore potential weight loss outcomes at different doses. Check your current BMI using our calculator above — it shows where you sit on the NHS weight categories and helps determine if you might be eligible for prescription support. You can also track your weight loss progress with our free progress tracker, whether you're using medication, diet, or both combined.
- 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 I lose weight by just changing my diet without exercise?
Yes — weight loss primarily comes from eating fewer calories than you burn, which diet can achieve alone. The NHS recommends a deficit of around 500 calories daily for safe, sustainable loss of 0.5–1 kg per week. However, adding exercise provides additional benefits: it protects muscle mass, improves heart health, and makes weight maintenance easier long-term.
What's the fastest way to lose weight without working out?
The fastest safe rate is 0.5–1 kg per week through calorie deficit. Faster loss (over 1.5 kg/week) risks muscle loss and other complications, and should only happen under medical supervision. Very low-calorie diets (under 800 kcal/day) require GP oversight. Prescription weight loss medication can accelerate results when combined with a reduced-calorie diet.
Can Wegovy or Mounjaro help me lose weight without exercise?
Yes — GLP-1 medications like Wegovy and Mounjaro work by reducing appetite and helping you feel fuller, making it easier to eat less and maintain a calorie deficit through diet alone. Clinical trials show weight loss without requiring specific exercise targets, though adding physical activity improves overall health outcomes. Both are prescription-only and require clinical assessment.
Do I need to exercise if I'm taking weight loss injections?
No — GLP-1 medications help weight loss through appetite reduction and don't require exercise to be effective. However, adding even light physical activity (walking, gentle strength work) boosts cardiovascular health, preserves muscle mass during weight loss, and improves long-term weight maintenance. Your prescriber can advise what's safe for your individual situation.
How do I access weight loss medication through the NHS in the UK?
Ask your GP for a referral to a specialist tier 3 or tier 4 weight management service. Eligibility requires a BMI of 30+ or 27+ with weight-related health conditions. NHS availability and waiting times vary significantly by region. Private access is available through UK-licensed prescribers online, following a clinical assessment, with no NHS referral needed.
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.