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 a Fruit Juice Cleanse Help With Weight Loss?
Fruit juice cleanses have become popular for weight loss, but the evidence shows they rarely deliver lasting results. A juice cleanse typically involves replacing solid food with fruit and vegetable juices for days or weeks. While you may see quick weight loss initially, most of this is water weight. Once you return to normal eating, the weight usually comes back. The NHS recommends sustainable approaches to weight management instead—combining gradual dietary changes with increased physical activity, rather than extreme restriction.
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 Juice Cleanses Don't Work for Long-Term Weight Loss
Fruit juice cleanses create rapid but unsustainable weight loss. Here's why they typically fail:
- Water weight loss, not fat loss: Initial weight drop is mostly water and glycogen depletion, not body fat.
- High sugar content: Fruit juice is calorie-dense and high in natural sugars—a 250ml glass can contain 20–30g of sugar with minimal fibre.
- Nutritional deficiencies: Juice-only diets lack protein, healthy fats, and essential nutrients your body needs.
- Metabolic slowdown: Very low-calorie intake can reduce metabolic rate, making weight regain easier.
- No sustainable habit change: Cleanses don't teach new eating behaviours, so old patterns return after the cleanse ends.
The NHS and most weight management specialists agree that gradual, sustainable dietary changes produce better long-term results than restrictive cleanses.
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.
Evidence-Based Approaches to Weight Loss in the UK
If you're looking for genuine, sustainable weight loss, the NHS recommends a multi-faceted approach:
- Calorie deficit with whole foods: A modest deficit (around 500 kcal/day) with balanced meals produces steady fat loss of approximately 0.5–1 kg per week.
- Regular physical activity: Combine dietary changes with at least 150 minutes of moderate activity weekly.
- Professional support: Your GP can refer you to NHS weight management services or recommend evidence-based programmes.
- Track progress: Monitor your weight and BMI regularly to stay motivated and adjust your approach if needed.
For adults meeting certain BMI and health criteria, prescription weight loss medications used alongside lifestyle changes may be an option—always discuss this with your GP or a licensed prescriber.
- 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 I lose weight fast on a juice cleanse?
You may lose weight quickly initially—often 2–5 kg in the first week—but this is mainly water and glycogen loss, not fat loss. Once you resume normal eating, the weight typically returns rapidly. Long-term sustainable weight loss requires gradual dietary and lifestyle changes, not restriction periods.
Is fruit juice cleanse safe?
Juice cleanses aren't dangerous for most people in the short term, but they lack protein and healthy fats, potentially causing fatigue, dizziness, and muscle loss. Very restrictive cleanses can disrupt blood sugar levels. If you have diabetes, kidney disease, or are pregnant, consult your GP before starting any cleanse.
Why do juice cleanses promise to "detox" your body?
Marketing claims about "detoxing" are misleading. Your liver and kidneys naturally filter waste without needing special cleanses. No scientific evidence supports the idea that juice cleanses remove toxins more effectively than your body already does. This is a marketing claim without solid backing.
What's a better alternative to a juice cleanse for weight loss?
The NHS recommends eating balanced meals in smaller portions, staying hydrated with water, and increasing physical activity. If you struggle with weight management, ask your GP about referral to tier 2 or tier 3 weight management services, where structured programmes and evidence-based options—including prescription medication if appropriate—are available.
Should I try a juice cleanse before using weight loss medication?
No. Prescription weight loss medications like GLP-1 injections work best alongside sustainable lifestyle changes, not extreme restriction. Use our free GLP-1 weight loss calculator to explore whether evidence-based medication options might suit you, and discuss this with your GP or a 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.