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 Juice Diets Work for Weight Loss?
Juice diets — often marketed as gradual weight management solutions — are popular in the UK but have significant limitations. While juices are low in calories, they lack the protein, fibre, and nutrients needed for sustainable weight management. The NHS recommends a balanced, calorie-controlled approach over restrictive diets. Our free BMI calculator can help you assess your current weight status, and our GLP-1 weight loss calculator shows evidence-based alternatives for those who need additional support beyond diet alone.
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 Diets Are Not Recommended by the NHS
Juice-only diets typically provide 400–800 calories per day — well below recommended intake — and cause rapid initial weight loss, but most is water and muscle, not fat. The NHS warns against very low-calorie diets without medical supervision.
- Nutrient deficiency: Juice lacks protein, healthy fats, and fibre essential for satiety and metabolic health
- Blood sugar spikes: High fruit sugar content causes rapid glucose surges and crashes, increasing hunger and cravings
- Muscle loss: Insufficient protein during calorie deficit leads to lean muscle breakdown, lowering metabolism
- Unsustainable: Extreme restriction typically results in rebound weight gain when normal eating resumes
- Dental damage: Concentrated fruit acids erode tooth enamel over time
The NHS weight loss guidance emphasises sustainable approaches: balanced meals with protein, whole grains, vegetables, and moderate calorie deficit (500 kcal/day for ~0.5 kg/week loss).
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 Alternatives for Weight Management UK
If juice diets appeal to you for rapid results, consider NHS-recommended alternatives. Prescription weight loss medication combined with lifestyle changes provides sustainable, medically-supported weight management for eligible adults. Those with a BMI of 30 or above, or 27 or above with weight-related health conditions, may qualify for treatment through NHS specialist services or private assessment.
Our free weight loss calculator helps estimate potential outcomes with evidence-based approaches. Consult your GP about personalised options for your situation — whether structured diet programmes, behaviour change support, or prescription medication options like GLP-1 therapy alongside reduced-calorie eating.
- 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.
Can you lose weight on a juice diet?
Yes, initially — but mostly water and muscle, not fat. Very low-calorie juice diets (400–800 kcal/day) cause gradual weight management that rebounds when normal eating resumes. The NHS recommends slower, sustainable loss: 0.5–1 kg per week through balanced diet and activity.
How much weight can you lose on juice cleanse?
A week-long juice cleanse typically shows 2–5 kg loss, but this is mostly water and glycogen depletion, not fat loss. After resuming normal diet, weight usually returns within days. There's no clinical evidence that "detox" juices offer lasting benefits.
Is juice diet safe for long-term weight loss?
No. Juice-only diets are unsafe long-term due to nutrient deficiency, muscle loss, and metabolic damage. The NHS advises against very low-calorie diets without medical supervision. Safe weight loss requires adequate protein, fibre, and whole foods — which juice diets lack.
What's better than a juice diet for losing weight?
NHS-recommended approaches: balanced meals (protein, vegetables, whole grains), 500 kcal daily deficit, increased activity, and behaviour change support. For those who need additional help, prescription weight loss medication combined with diet changes offers evidence-based results.
Can juice diet help with BMI?
Temporarily — juice diets lower BMI quickly, but gains return rapidly. For lasting BMI improvement, use our BMI calculator to set realistic healthy weight targets (18.5–24.9), then pursue sustainable calorie reduction and physical activity recommended by your GP.
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.