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
How Much Weight Can You Lose in 5 Weeks?
Losing weight over 5 weeks is achievable with the right approach, though realistic expectations matter. The NHS recommends losing 0.5 to 1 kg per week for sustainable results — meaning 2.5 to 5 kg over 5 weeks is a realistic target. This timeframe is short enough to see meaningful progress, but long enough to establish healthier habits. Your actual results depend on starting weight, diet, activity level, and individual metabolism. Use our free BMI calculator to assess your current weight status, and our weight converter to track progress in stone and pounds if you prefer UK measurements.
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.
Safe Weight Loss Rates and What to Expect
The NHS advises a safe weight loss rate of 0.5 to 1 kg (1 to 2 lbs) per week. This pace minimises muscle loss, keeps energy levels steady, and helps your body adjust to new habits. Over 5 weeks, this means expecting roughly 2.5 to 5 kg of weight loss.
Faster loss is sometimes possible with medical supervision or prescription weight loss medication, but carries higher risks. Very gradual weight management can cause muscle loss, nutritional deficiencies, and fatigue.
- Week 1: Often includes initial fluid loss (0.5–1.5 kg)
- Weeks 2–5: Gradual fat loss through calorie deficit (0.5–1 kg per week)
- Total realistic range: 2.5–5 kg over 5 weeks
Individual results vary widely based on genetics, starting weight, and lifestyle. Our GLP-1 weight loss calculator can help estimate projected losses if you're considering prescription weight loss medication as part of your approach.
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.
How to Achieve Weight Loss in 5 Weeks
A calorie deficit of around 500 kcal per day typically results in approximately 0.5 kg weekly loss. This can be achieved through diet, exercise, or a combination.
- Diet: Focus on whole foods, vegetables, lean protein, and reduced processed foods. Even modest portion control yields results
- Physical activity: Aim for 150 minutes moderate activity weekly plus 2 days strength training
- Hydration and sleep: Both support metabolism and reduce false hunger signals
- Consistency: Small daily changes compound significantly over 5 weeks
If weight management is challenging through lifestyle alone, your GP can discuss NHS weight loss services, prescription options like GLP-1 medication, or specialist referral. Track your progress using our free progress tracker to stay motivated.
- 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 I support gradual weight management safely?
No. Losing 10 kg in 5 weeks (2 kg per week) is not considered safe without close medical supervision. The NHS recommends 0.5–1 kg weekly for sustainable results. Faster loss risks muscle loss, nutrient deficiencies, and metabolic slowdown. Always aim for gradual, steady progress.
What role can prescription weight loss medication play in 5 weeks?
Prescription GLP-1 medications like Wegovy (semaglutide) may support weight loss when used with dietary changes. However, doses are typically escalated slowly over weeks 1–4, so maximum effect may not be reached within 5 weeks. Results vary individually. Your GP or prescriber can assess if this is appropriate for you.
Is 5 weeks enough time to see real progress?
Yes. At a safe rate of 0.5–1 kg per week, you can realistically lose 2.5–5 kg in 5 weeks. This is enough to notice physical changes, improved energy, and reduced bloating. More importantly, 5 weeks establishes healthy habits that sustain longer-term weight management.
How do I know if my weight loss is on track?
Use a combination of scales and how you feel. Weekly weigh-ins (same time, same day) show trends. Initial weeks often show faster loss due to water weight — this naturally slows. Check your BMI using our free BMI calculator to see if you're moving toward a healthier range. Photos and measurements also reveal progress the scales may not.
What's the difference between weight loss medication and lifestyle changes alone?
Lifestyle changes (diet and exercise) work for many people but require significant willpower. Prescription weight loss medication like GLP-1 injections may support appetite regulation alongside lifestyle changes, helping some people achieve results more easily. Evidence suggests combined approaches work better than either alone for weight management in the UK.
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.