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
Is Swimming Good for Weight Loss?
Swimming is an excellent form of physical activity that can support weight loss when combined with a balanced diet. It burns significant calories, builds lean muscle, and improves cardiovascular health without putting stress on your joints. However, weight loss ultimately depends on creating a calorie deficit — the difference between calories consumed and burned. For many UK adults, combining regular swimming with other lifestyle changes or prescription weight management medication may help achieve sustainable results. Calculate your current BMI using our free BMI calculator to understand your personal health context and explore all available weight management 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.
Swimming and Weight Loss — What the Evidence Shows
Swimming is a high-calorie-burning activity suitable for most fitness levels. A 70 kg adult can burn approximately 400–600 calories during an hour of moderate to vigorous swimming, depending on stroke intensity and speed. This makes it an effective component of any weight management UK programme.
Swimming also offers unique benefits:
- Low-impact exercise — reduces joint stress compared to running
- Builds lean muscle mass across the entire body
- Improves cardiovascular fitness and lung capacity
- Suitable for people of various ages and fitness levels
- Can be sustained long-term without injury risk
However, swimming alone is not assured to produce weight loss. Research shows that exercise combined with dietary changes produces better outcomes than exercise alone. For individuals with a BMI above 30 or significant weight-related health conditions, prescription weight loss medication alongside exercise and diet may be recommended by healthcare professionals.
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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 in the UK
Three prescription medications are licensed for weight management in the UK: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These work by helping regulate appetite and supporting feeling fuller after meals, allowing individuals to maintain a reduced-calorie diet more effectively.
Eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Access is available through NHS specialist weight management services (tier 3) following a GP referral, or through private prescribing. Try our free GLP-1 weight loss calculator to estimate potential results at different medication doses, then discuss options with your GP or a licensed prescriber to determine what is appropriate for your individual circumstances.
- 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.
How many calories does swimming burn per hour?
A 70 kg adult typically burns 400–600 calories during an hour of moderate to vigorous swimming, depending on stroke speed and intensity. This varies based on body weight, fitness level, and effort — heavier individuals burn more calories in the same activity. Use our weight converter to check your weight in kg if needed.
Is swimming better than other exercises for weight loss?
Swimming is highly effective because it burns significant calories whilst being low-impact. However, the best exercise for weight loss is one you'll do consistently. Running may burn more calories per hour; cycling is also excellent. The key is regular activity combined with a calorie deficit from diet. Weight loss ultimately depends on overall energy balance, not exercise type alone.
Can I lose weight with swimming alone, without changing my diet?
Weight loss requires a calorie deficit — burning more energy than you consume. Swimming without dietary changes may result in minimal loss because eating habits often offset calories burned through exercise. For sustainable results, the NHS recommends combining regular physical activity with balanced nutrition. For some individuals, prescription weight loss medication can support this approach.
What prescription weight loss options are available in the UK?
Three medications are UK-licensed for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All are prescription-only and require a clinical assessment. Access is through NHS specialist services or private prescribers. Eligibility depends on BMI and health conditions. Your GP can discuss whether you may be suitable.
How do I find out if I'm eligible for weight loss medication in the UK?
Start by speaking with your GP, who can assess your BMI, health history, and any weight-related conditions. You can also use our free BMI calculator on this page to check your current BMI against NHS guidelines. For private assessment, licensed online prescribers offer consultations. Eligibility criteria include BMI ≥30, or BMI 27–29.9 with conditions like diabetes or high blood pressure.
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.