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 Seltzer Water Help With Weight Loss?
Seltzer water is often promoted as a weight loss aid, but the evidence is more nuanced than marketing suggests. Plain seltzer water itself contains no calories and won't directly cause weight loss, but it may support weight management efforts when used as part of a broader strategy. Understanding how carbonated water fits into evidence-based weight loss is important for setting realistic expectations about nutrition and sustainable weight management in the UK.
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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 Seltzer Water Might Support Weight Management
Plain seltzer water (carbonated water with no added sugar, sweeteners, or flavourings) is calorie-free and may offer minor benefits within a weight loss plan:
- Increases fluid intake — staying hydrated supports metabolism and can reduce false hunger signals
- Creates fullness — the carbonation can create a sense of satiety, potentially reducing overall calorie intake at meals
- Replaces sugary drinks — swapping regular soft drinks for seltzer eliminates hundreds of calories weekly
- Supports hydration without energy — unlike juice or fizzy drinks, plain seltzer adds no sugar or artificial sweeteners
However, seltzer water is not a weight loss tool in itself. Weight loss requires a sustained calorie deficit, which is achieved through dietary choices and physical activity. Use our free BMI calculator to understand your current weight status, and our GLP-1 weight loss calculator to explore evidence-based approaches to weight management in the UK.
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.
What Actually Drives Weight Loss
Sustainable weight loss depends on three factors: calorie deficit, physical activity, and consistent behaviour change. The NHS recommends losing 0.5 to 1 kg per week through a combination of reduced-calorie diet and increased movement. No single food or drink — including seltzer water — creates weight loss alone.
For individuals with a BMI of 30 or above, or 27–29.9 with weight-related health conditions, prescription weight loss medication (like GLP-1 injections such as Wegovy or Mounjaro) may support efforts alongside lifestyle changes. These are prescription-only and require clinical assessment. Track your progress with our free progress tracker to monitor actual results over time.
- 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.
Does seltzer water burn fat?
No. Seltzer water contains no calories and cannot burn fat on its own. Weight loss requires a calorie deficit created through diet and exercise. Seltzer can be part of a broader strategy by helping you stay hydrated and replacing sugary drinks, but it is not a fat-burning tool.
Is seltzer water better than diet soft drinks for weight loss?
Yes, plain seltzer is preferable to diet soft drinks. While diet drinks contain no calories, some evidence suggests artificial sweeteners may affect appetite regulation. Plain seltzer with no additives is the best carbonated option within a weight management plan.
Can carbonation affect weight loss?
Carbonation itself does not affect weight loss. However, the bubbles may create a feeling of fullness, which could reduce meal portion sizes. This modest effect only helps if it leads to a genuine calorie deficit over time.
How much weight can I lose by drinking seltzer water?
Drinking seltzer water alone will not result in weight loss. You must create a calorie deficit through food choices and activity. If seltzer replaces sugary drinks, you may lose weight — but the loss comes from the calorie reduction, not the seltzer itself.
What is the most effective way to lose weight in the UK?
The NHS recommends a combination of reduced-calorie eating (approximately 500 kcal deficit daily) and physical activity targeting 0.5–1 kg weight loss per week. For BMI over 30, or 27+ with health conditions, your GP can refer you to specialist weight management services or prescription options like GLP-1 medication.
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.