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 Laxatives Help Weight Loss?
Laxatives do not help with genuine weight loss and can be harmful if misused. While they may cause temporary weight reduction on the scales, this is water and stool weight — not fat loss. Using laxatives for weight management is unsafe and ineffective. The NHS recommends evidence-based approaches like reduced-calorie diets, increased physical activity, and prescription weight management options when appropriate. Understanding the difference between temporary water loss and sustainable fat loss is essential for healthy weight management in the UK.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Why Laxatives Don't Support Real Weight Loss
Laxatives work by stimulating bowel movements and increasing water loss — not fat loss. Any weight reduction seen on scales is temporary and typically returns within hours of rehydration. This creates a dangerous cycle: people use laxatives repeatedly, believing they're losing weight, when in reality they're only losing fluid and electrolytes.
The key distinction: fat loss requires a calorie deficit over time. Laxatives bypass digestion entirely and don't reduce calorie intake — they simply speed up elimination of food already consumed. The NHS confirms that sustainable weight loss of 0.5 to 1 kg per week comes from dietary changes and physical activity, not from laxative use.
Misusing laxatives carries real health risks: dehydration, electrolyte imbalance, digestive system damage, nutrient malabsorption, and dependency. People can develop a reliance where their bowels no longer function normally without laxatives.
Clinically BackedWeight Loss
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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.
Evidence-Based Weight Loss That Actually Works
Sustainable weight management involves creating a calorie deficit through balanced nutrition and activity. For effective weight management in the UK, the NHS supports: structured calorie-reduction diets, increased physical activity, behaviour change programmes, and prescription weight loss medications when clinically appropriate.
If you're struggling with weight management, start by calculating your BMI and speaking with your GP. Prescription options like GLP-1 weight loss injections are available through NHS specialist services or private prescribing if you meet eligibility criteria — these work through appetite regulation, not fluid loss. Track your progress sustainably with proper tools and professional guidance, not dangerous shortcuts like laxatives.
- 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.
Will laxatives help me lose weight quickly?
No. Laxatives cause temporary fluid loss, not fat loss. Any weight reduction is water and stool weight that returns immediately after rehydration. This doesn't constitute real weight loss and can be dangerous if repeated.
Why do laxatives show weight loss on the scales?
Laxatives increase bowel movements and water loss, which shows as reduced weight temporarily. However, this is not fat loss — it's dehydration. Once you drink fluids, the weight returns within hours.
What are the health risks of using laxatives for weight loss?
Misuse can cause severe dehydration, electrolyte imbalance, nutrient deficiencies, bowel damage, and dependency. Your digestive system can stop functioning normally without them, creating a harmful cycle.
What does the NHS recommend for weight loss instead?
The NHS recommends sustainable approaches: reduced-calorie diets (targeting 0.5–1 kg per week loss), increased physical activity, behaviour change support, and prescription weight loss medications when appropriate. Your GP can assess what's suitable for you.
Are there prescription weight loss options available in the UK?
Yes. GLP-1 weight loss medications like Mounjaro and Wegovy are available through NHS specialist weight management services or private prescribing. These work by regulating appetite and supporting healthy eating habits — not through dangerous fluid loss.
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.