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
Weight Loss Countdown — How to Get Started
A weight loss countdown is a structured plan to help you reach your target weight within a realistic timeframe. Rather than aiming for overnight transformation, a countdown breaks your goal into manageable phases, helping you stay motivated and track progress effectively. Whether through lifestyle changes alone or with medical support like GLP-1 weight loss medication, understanding the realistic timeline for weight management in the UK is essential for sustainable results.
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 Long Does Healthy Weight Loss Take?
The NHS recommends losing weight at a rate of 0.5 to 1 kg per week for sustainable, healthy results. This translates to losing approximately 2–4 kg per month. At this pace, you can expect to lose roughly 6–12 kg over three months, or 12–26 kg within six months.
- A calorie deficit of around 500 kcal daily typically results in 0.5 kg weekly loss
- Faster loss (over 1.5 kg weekly) is not recommended without medical supervision
- Very low calorie diets (under 800 kcal daily) require close GP monitoring
- Individual results vary based on age, metabolism, starting weight, and activity level
Use our free BMI calculator above to establish your current weight status, then calculate your target weight range. Our weight loss projection calculator can help you estimate realistic timescales for reaching your goal with GLP-1 medication support.
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.
Creating Your Weight Loss Countdown Plan
A practical weight loss countdown involves setting clear milestones and reviewing progress regularly. Break your total goal into 3-month targets, then smaller monthly checkpoints. Track your weight weekly using our free progress tracker to monitor patterns without obsessing over daily fluctuations.
For prescription weight loss medication through NHS weight management services or private prescribing, your countdown will depend on your dose escalation schedule. Mounjaro and Wegovy typically take 4–8 weeks to reach maintenance doses, with meaningful weight loss appearing around weeks 8–12. Always consult your GP or a licensed prescriber to establish a realistic timeline based on your health status and eligibility.
- 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.
How do I calculate my weight loss countdown?
Decide your target weight using our BMI calculator (healthy range is 18.5–24.9 BMI for most adults). Calculate the difference from your current weight, then divide by 0.5 kg weekly loss. For example, losing 10 kg at 0.5 kg/week = 20 weeks. Our weight converter helps compare targets in stone and kilograms.
Can GLP-1 medication speed up my weight loss countdown?
Yes. Clinical trials showed Wegovy (semaglutide) resulted in approximately 15% average body weight loss, and Mounjaro (tirzepatide) showed 15–21% loss. However, these are prescription-only medications requiring clinical assessment. Results vary individually, and they work alongside reduced-calorie diet and physical activity, not instead of them.
Is gradual weight management safer than a long countdown?
No. gradual weight management (over 1.5 kg weekly) increases risk of muscle loss, gallstones, nutritional deficiency, and metabolic slowdown. The NHS recommends 0.5–1 kg weekly for sustainable results. Faster loss is only considered under medical supervision for specific health reasons.
What should I do if my weight loss stalls?
Weight loss plateaus are normal, especially after 8–12 weeks. Review your calorie intake, increase physical activity, or adjust meal timing. If using prescription medication, your prescriber may adjust your dose. Keep tracking with our progress tool—natural fluctuations happen; focus on the overall trend over 4 weeks.
How does NHS weight loss support fit into my countdown?
NHS weight management services (tier 3) provide specialist support including dietitian advice, behaviour change support, and prescription medication options. Waiting times vary by region, but specialist services significantly improve success rates for sustainable weight management timescales.
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.