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
Weight Loss Cleanse — What the Evidence Actually Shows
A weight loss cleanse isn't a single medical treatment — it's a term people use for various detox diets, juice cleanses, or gradual weight management programmes. The NHS and medical evidence suggest that sustainable weight loss comes from consistent calorie reduction and lifestyle changes, not quick-fix cleanses. If you're looking to lose weight, understanding what actually works — and what doesn't — is key to achieving lasting results. Let's break down the science behind weight loss cleanses and explore which approaches have real evidence behind them.
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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.
Do Weight Loss Cleanses Actually Work?
Weight loss cleanses typically promise rapid results through strict dieting, juice fasting, or special supplements. However, any initial weight loss is usually water and muscle loss, not fat loss — and the weight often returns quickly once normal eating resumes.
The NHS recommends losing weight at a rate of 0.5 to 1 kg per week for sustainable results. This requires a calorie deficit of around 500 kcal per day. Research shows that:
- Extreme calorie restriction (under 800 kcal/day) causes muscle loss and metabolic slowdown
- Juice cleanses lack protein and nutrients needed for healthy weight loss
- Detox products have no scientific evidence behind them — your liver and kidneys naturally detox your body
- Weight lost through cleanses typically returns within weeks or months
If you want real, lasting weight management in the UK, focus on approaches with proven results: reduced-calorie eating, increased physical activity, and behaviour change. Use our free BMI calculator above to check your starting point and track progress with our progress tracker.
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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.
What Actually Works for Weight Loss
Evidence-based weight loss approaches include balanced eating with a calorie deficit, regular physical activity, and addressing eating habits. The NHS Weight Loss Plan offers free guidance and support.
For some adults, prescription weight loss medication may be appropriate alongside these lifestyle changes. GLP-1 injections like Wegovy (semaglutide) are licensed for weight management in the UK and have clinical trial evidence supporting their use. Clinical trials showed that adults using Wegovy lost an average of around 15% of body weight over 68 weeks — though individual results vary significantly. These are prescription-only medicines requiring clinical assessment by a GP or licensed prescriber. Try our GLP-1 weight loss calculator above to explore how medication might support your goals, and our weight converter to track weight changes across different units.
- 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.
Is a juice cleanse a safe way to lose weight?
Juice cleanses can cause rapid water weight loss but lack protein, fibre, and essential nutrients. They don't burn fat and are not recommended by the NHS for sustainable weight loss. Any weight lost usually returns quickly. Instead, focus on balanced eating with a calorie deficit of around 500 kcal per day, which supports healthy loss of 0.5–1 kg per week.
Do detox supplements really help you lose weight?
Detox supplements have no scientific evidence behind them. Your liver and kidneys naturally detoxify your body without supplements. Marketing claims are often unproven. Safe weight loss comes from eating fewer calories than you burn, combined with increased physical activity — not from detox products.
How quickly can you lose weight safely?
The NHS recommends losing 0.5 to 1 kg (1 to 2 lbs) per week. This requires a calorie deficit of about 500 kcal per day and supports loss of fat rather than muscle. Faster weight loss without medical supervision can lead to muscle loss, nutritional deficiencies, and metabolic slowdown. Sustainable results take time.
What should I do instead of a weight loss cleanse?
The NHS recommends a balanced diet with a calorie deficit, regular physical activity, and behaviour change support. The free NHS Weight Loss Plan offers guidance. For eligible adults, prescription weight loss medication like GLP-1 injections may be appropriate alongside lifestyle changes. Speak to your GP to discuss which approach suits you.
Are weight loss injections better than cleanses?
GLP-1 injections like Wegovy are prescription-only medicines with clinical trial evidence showing they can support weight loss of around 15% body weight on average — when used alongside diet and exercise. Unlike cleanses, they work by regulating appetite hormones. However, prescription weight loss medication is only suitable for some people and requires clinical assessment by a GP or licensed prescriber.
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.