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
4 Week Weight Loss Plan — Realistic Goals and Safe Strategies
A 4 week weight loss plan can kickstart your journey towards better health, but realistic expectations are crucial. Over 4 weeks, the NHS recommends aiming to lose 2–4 kg (4–9 lbs) through sustainable lifestyle changes — a safe rate of 0.5–1 kg per week. This timeframe is ideal for establishing new habits with food and activity, though significant weight management often requires longer-term commitment. Your GP can provide personalised guidance, and understanding your starting point using your BMI helps set appropriate targets aligned with NHS weight management guidance.
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.
What Can You Realistically Lose in 4 Weeks?
Safe weight loss over 4 weeks depends on creating a calorie deficit. The NHS recommends losing no more than 0.5–1 kg per week, which typically requires a deficit of 500 kcal per day. This means realistic 4-week targets range from 2–4 kg (4–9 lbs), though individual results vary significantly based on starting weight, metabolism, and adherence to dietary changes.
Very gradual weight management (more than 1.5 kg per week) increases the risk of muscle loss, nutrient deficiency, and unsustainable habits. A 4-week plan works best as the start of a longer-term commitment rather than a structured approach. For weight loss medication options like GLP-1 injections, prescription weight loss medications are also available through NHS specialist services or private prescription in the UK, though these are typically used as part of longer strategies (12 weeks or more).
- Realistic loss: 2–4 kg over 4 weeks at safe deficit
- Daily calorie reduction needed: approximately 500 kcal
- Faster loss is possible but increases health risks
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.
Building a Sustainable 4 Week Plan — Practical Steps
A successful 4-week weight loss plan combines dietary change, increased physical activity, and behaviour tracking. Start by calculating your BMI to understand your baseline health status, then use our free BMI calculator to set a realistic target range aligned with NHS healthy weight guidance.
Record what you eat and drink daily — awareness alone often leads to better choices. Aim for 150 minutes of moderate activity weekly (brisk walking, cycling, swimming). Drink plenty of water, prioritise protein-rich foods to preserve muscle, and reduce sugary drinks and processed snacks. Track your progress weekly to stay motivated and adjust habits if needed. If you're considering prescription weight loss support, arrange a consultation with your GP to discuss whether medication might support your plan.
- 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 much weight can I safely lose in 4 weeks?
The NHS recommends losing 0.5–1 kg per week through sustainable lifestyle changes, making a realistic 4-week target 2–4 kg (4–9 lbs). Faster loss increases risks of muscle loss and nutrient deficiency. Individual results vary based on starting weight, diet adherence, and activity level.
What's the best diet for a 4 week weight loss plan?
The most effective diet is one you can stick to. Evidence supports reduced-calorie eating with whole foods, adequate protein, plenty of vegetables, and limited processed foods. The Mediterranean diet has strong evidence for sustainable health. Consistency matters more than restrictive approaches. Your GP can advise on dietary approaches suitable for your health profile.
Should I use the BMI calculator to check my progress?
Yes. Calculate your BMI at the start of your 4-week plan using our free BMI calculator, then check it at the end. BMI doesn't account for muscle gain, so also track how you feel, energy levels, and how clothes fit. Weight can fluctuate daily due to water retention and digestion — weekly weigh-ins are more reliable than daily checks.
Can weight loss injections help with a 4 week plan?
Prescription weight loss medications like GLP-1 injections (Mounjaro, Wegovy) are available through NHS specialist services or private prescription in the UK. These work alongside diet and activity changes. Results typically develop over weeks and months, not days, so they're best viewed as part of longer-term weight management rather than rapid 4-week solutions. Your GP can assess suitability.
What should I do if I'm not losing weight after 4 weeks?
Weight loss plateaus are normal. Review your calorie intake — you may need a larger deficit as your weight decreases. Increase activity, check portion sizes, and ensure you're not underestimating calories consumed. If you've made genuine dietary and activity changes for 4 weeks without progress, speak to your GP, who may suggest referral to NHS weight management services or consider whether medication could help.
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.