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 Six Months?
Losing weight over six months is an achievable goal with realistic expectations and the right approach. The NHS recommends losing weight at a steady rate of 0.5 to 1 kg per week through a combination of dietary changes and increased physical activity. Over six months, this means a potential weight loss of 13 to 26 kg. However, individual results vary significantly depending on your starting weight, metabolism, age, and the methods you use. Whether you're managing your weight through lifestyle changes alone or with support from prescription weight loss medication, understanding what's realistic helps you stay motivated and avoid disappointment.
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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.
Safe Weight Loss Rates and Six Month Timelines
The NHS recommends losing no more than 0.5 to 1 kg per week for sustainable, healthy weight loss that preserves muscle mass and is easier to maintain long-term. At this rate over 26 weeks (six months), you could expect to lose between 13 and 26 kg, though actual results depend on many factors.
A calorie deficit of around 500 kcal per day typically results in approximately 0.5 kg weekly loss, whilst a 1000 kcal deficit may produce 1 kg weekly loss. Very gradual weight management (more than 1.5 kg per week) is not recommended without medical supervision, as it increases the risk of muscle loss, gallstones, nutrient deficiencies, and weight regain.
- Gradual loss is more sustainable and easier to maintain
- Rapid loss often leads to muscle loss alongside fat loss
- Combining diet and exercise produces better long-term results than diet alone
- Individual factors (age, gender, starting weight, metabolism) significantly affect results
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.
Six Month Weight Loss with Prescription Medication
For weight management in the UK, prescription medications such as GLP-1 injections (Wegovy) or dual GIP/GLP-1 injections (Mounjaro) may be prescribed alongside lifestyle changes. Clinical trials showed that GLP-1 weight loss medications can support additional weight loss beyond diet and exercise alone.
In the STEP-1 trial, Wegovy (semaglutide) helped participants lose an average of approximately 15% of their body weight over 68 weeks — though individual results vary. Prescription weight loss medications are prescription-only and require a clinical assessment by your GP or a licensed prescriber to determine suitability. Try our GLP-1 weight loss calculator to explore potential results at different doses, and use the progress tracker to monitor your journey over the six-month period.
- 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.
What's a realistic weight loss goal for six months?
The NHS recommends 0.5 to 1 kg per week, meaning 13–26 kg over six months. This depends on your starting weight, diet, exercise, age, and metabolism. Individual results vary significantly. Your GP can help set realistic targets based on your health.
Can you lose weight faster in six months?
Faster loss (more than 1.5 kg per week) is possible but not recommended without medical supervision. Rapid loss increases muscle loss risk and is harder to maintain. Steady, gradual loss is more sustainable and healthier long-term.
How does prescription weight loss medication affect six month results?
GLP-1 medications like Wegovy may support weight loss alongside diet and exercise. Clinical trials showed average loss of around 15% body weight over similar timeframes, but results vary individually. Medication requires prescription and clinical assessment.
What's the best way to lose weight in six months?
Combine a sustainable calorie deficit (500 kcal/day for 0.5 kg weekly loss), regular physical activity, and consistent dietary habits. Prescription medication may be an option if clinically appropriate. Use our BMI calculator to track progress and adjust as needed.
Should I track my weight loss progress weekly?
Weekly weigh-ins can be helpful but aren't essential. Weight fluctuates daily due to water, food intake, and hormones. Tracking monthly or bi-weekly provides a clearer picture. Our free progress tracker helps you monitor trends over six months without obsessing over daily changes.
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.