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 You Need to Exercise on Mounjaro or Wegovy?
No, you do not have to exercise to use Mounjaro or Wegovy, but physical activity significantly improves weight loss results and overall health outcomes. Both medications work best when combined with a reduced-calorie diet and increased physical activity. NHS guidance emphasises that prescription weight loss injections are tools to support lifestyle changes, not replacements for them. Individual results vary, and many people achieve weight loss on either medication without structured exercise, though adding movement amplifies benefits.
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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 Mounjaro and Wegovy Work Without Exercise
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) work by reducing appetite and helping you feel fuller after smaller meals, independently of exercise. The medications activate GLP-1 pathways (Wegovy uses a single GLP-1 agonist mechanism, while Mounjaro uses dual GIP and GLP-1 receptor agonist action) that naturally suppress hunger signals. Clinical trials showed weight loss occurred without mandatory exercise programmes. However, the NHS and NICE recommend combining any weight loss medication with lifestyle changes for best outcomes. Exercise amplifies results but is not a prerequisite for the medications to function at a metabolic level. Many people taking either medication through private prescription or NHS routes experience weight reduction through dietary changes alone, though sustainability and long-term health benefits improve with physical activity included.
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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.
Exercise Recommendations While on Mounjaro or Wegovy
If you can exercise, NHS guidance recommends at least 150 minutes of moderate aerobic activity weekly, plus strength training twice weekly—the same advice for all UK adults. Starting small is important, especially if you have not exercised recently. Many people find that as appetite decreases on Mounjaro or Wegovy (even at the starting dose during the KwikPen titration phase), they naturally have more energy for movement. Your prescriber can discuss realistic activity goals during your clinical assessment. Walking, swimming, cycling, and strength training all count. Remember that weight loss on medication alone can reduce joint stress, making exercise easier to begin. The combination of reduced calorie intake from the medication plus physical activity creates the best health outcomes, but neither is mandatory for the medication to work.
- 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 you have to exercise to lose weight on Mounjaro?
No. Mounjaro works by reducing appetite and food intake regardless of exercise level. Clinical trials showed weight loss without structured exercise programmes. However, adding physical activity improves results and long-term health outcomes. Many people achieve weight loss through dietary changes alone while taking the medication.
Is exercise mandatory on Wegovy?
No. Wegovy (semaglutide) reduces hunger independently of physical activity. NHS and clinical evidence show weight loss occurs with diet changes alone. Exercise is recommended to maximise results and cardiovascular health, but it is not required for the medication to be effective.
What exercise is safe while taking Mounjaro or Wegovy?
Any moderate activity is safe: walking, swimming, cycling, strength training. Start gently if you are not used to exercise. As appetite decreases during dose titration, many people naturally feel more energetic. Discuss realistic goals with your prescriber during your clinical assessment.
Do Mounjaro and Wegovy work better with exercise?
Yes. Combining either medication with a calorie deficit plus physical activity produces better weight loss and cardiovascular health than medication or exercise alone. However, individual results vary. Both approaches—medication with diet only, or medication with diet plus exercise—show weight loss in clinical trials.
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.