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
7 Day Liquid Diet Weight Loss Results — What to Expect
A 7-day liquid diet can produce rapid initial weight loss, typically 1–3 kg (2–7 lbs), though results vary significantly depending on your starting weight, metabolism, and calorie deficit. Most of this loss is water weight and glycogen depletion rather than fat loss. While liquid diets may offer short-term results, the NHS recommends sustainable weight loss of 0.5–1 kg per week for long-term success. If you're considering gradual weight management methods, it's worth understanding what realistic outcomes look like and discussing options with your GP.
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.
How Much Weight Can You Lose in 7 Days?
A 7-day liquid diet typically produces weight loss of 1–3 kg (2–7 lbs), though individual results depend on starting weight and baseline metabolism. Here's what actually happens:
- Days 1–3: Rapid loss (1–2 kg) — mostly water and glycogen from muscles, not fat
- Days 4–7: Slower loss (0.5–1 kg) — more likely to include fat loss as glycogen depletes
- Post-diet rebound: 50–70% of weight often returns within days as you resume normal eating — water and glycogen stores replenish
The NHS weight loss calculator suggests sustainable methods alongside dietary changes typically produce more lasting results than very restrictive short-term approaches. For genuine fat loss, a consistent calorie deficit of around 500 kcal per day is more effective than extreme restriction.
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.
Is a 7-Day Liquid Diet Safe and Sustainable?
Liquid-only diets are not recommended as a routine weight management strategy. The NHS advises against very low-calorie diets (under 800 kcal/day) without medical supervision. Short-term risks include fatigue, dizziness, headaches, and muscle loss. More importantly, rapid regain is common because the diet doesn't address eating habits or long-term weight management UK patterns.
For sustainable weight loss, the NHS recommends combining modest calorie reduction with increased physical activity. If you need structured support, discuss nhs weight loss options with your GP — these might include referral to tier 3 specialist services or evidence-based programmes. Some people with qualifying BMI thresholds may be eligible for prescription weight loss medication like GLP-1 injections, which work alongside lifestyle changes rather than replacing them.
- 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 keep the weight off after a 7-day liquid diet?
Most people regain 50–70% of the weight within 1–2 weeks because the diet doesn't change eating habits long-term. Sustainable weight loss requires ongoing dietary and activity changes, not short-term restriction.
Is a 7-day liquid diet medically safe?
Very restrictive liquid diets (under 800 kcal/day) are not recommended without medical supervision. The NHS advises against them for routine weight management. Side effects can include fatigue, dizziness, and muscle loss. Always consult your GP before starting any extreme diet.
What's the difference between water weight loss and fat loss?
Initial rapid loss on liquid diets is mostly water and glycogen (carbohydrate stores), not fat. Fat loss requires a sustained calorie deficit over weeks. Only after glycogen depletes does fat loss become the primary weight loss mechanism.
What are NHS-recommended alternatives to crash diets?
The NHS recommends losing 0.5–1 kg per week through modest calorie reduction (around 500 kcal deficit daily) plus physical activity. Referral to specialist weight management services, evidence-based programmes, or discussing glp-1 weight loss options with your GP are evidence-based alternatives.
Can I use the BMI calculator to set a realistic weight loss goal?
Yes. Use our free BMI calculator to find your current BMI and the healthy weight range for your height. Aiming for the healthy BMI range (18.5–24.9) sets a realistic long-term target — then work backwards to plan sustainable monthly loss rather than extreme weekly targets.
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.