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 — but it requires a calorie deficit through diet and, in some cases, prescription medication. The NHS confirms that weight loss is primarily driven by what you eat, not just how much you move. While physical activity has important health benefits, sustainable weight management is achievable through dietary changes alone, and prescription weight loss medication like Mounjaro or Wegovy can support this approach when used alongside reduced-calorie eating.
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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 fundamentally depends on consuming fewer calories than your body burns — this is called a calorie deficit. You do not need to exercise to create this deficit; you can achieve it through diet alone. The NHS recommends a deficit of around 500 calories per day to lose approximately 0.5 kg per week sustainably.
Your basal metabolic rate (BMR) — the calories you burn at rest — is responsible for the majority of your daily energy expenditure, even without formal exercise. This means eating less than your BMR allows will result in weight loss regardless of activity level.
- A reduced-calorie diet creates the deficit
- No gym time or structured workouts required
- Prescription weight loss medication can support dietary changes
- Progress tracking helps maintain consistency
Many people lose weight successfully through dietary changes alone, particularly those with physical limitations, mobility issues, or busy schedules. However, the NHS also emphasises that adding any physical activity — even gentle movement like walking — provides additional cardiovascular and mental health benefits beyond weight loss.
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 Without Exercise
GLP-1 medications like Wegovy and Mounjaro are prescription-only weight loss injections licensed in the UK that can support weight management when diet alone is not enough. These medications work by reducing appetite and increasing feelings of fullness, making it easier to maintain a calorie deficit without exercise.
In the STEP-1 clinical trial, participants using Wegovy (semaglutide) at 2.4 mg achieved an average weight loss of approximately 15% body weight over 68 weeks, alongside a reduced-calorie diet — no specific exercise requirement. Mounjaro (tirzepatide) showed average weight loss of 15–21% in clinical trials using the same approach.
Important: These are prescription-only medications requiring a clinical assessment with a UK-licensed prescriber. Eligibility includes adults with a BMI of 30 or above, or 27 or above with weight-related health conditions. Try our free GLP-1 weight loss calculator to explore potential outcomes, and use our BMI calculator to assess your current category.
- 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 you really lose weight by just changing your diet?
Yes. Weight loss requires a calorie deficit, which you can create entirely through diet. The NHS confirms that eating fewer calories than your body burns results in weight loss, regardless of exercise. Most weight loss comes from dietary changes; exercise provides additional health benefits but is not essential for losing weight itself.
How much weight can you lose without exercising?
Safe, sustainable weight loss is typically 0.5–1 kg per week through a 500 kcal daily deficit created by diet alone. Actual results vary based on your starting weight, metabolic rate, and consistency. Use our BMI calculator and weight loss calculator to estimate realistic targets for your situation.
What is the best diet for weight loss without exercise?
The NHS recommends any approach that creates a sustainable calorie deficit: Mediterranean diet, intermittent fasting, or simply eating smaller portions of balanced meals. The most effective diet is one you can stick to long-term. Low calorie diets (800–1200 kcal daily) should only be followed under medical supervision.
Can prescription weight loss injections help without exercise?
Yes. GLP-1 medications like Wegovy and Mounjaro are licensed for weight management and can support weight loss through reduced appetite, even without formal exercise. Clinical trials showed significant weight loss using these medications alongside dietary changes alone. Prescription and clinical assessment required.
What should I do if diet alone is not working?
If you have been maintaining a calorie deficit through diet for several months without adequate progress, speak to your GP. You may be eligible for prescription weight loss medication through NHS specialist services or private prescribing. Your GP can assess whether medication is appropriate for you.
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.