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
Immediate Weight Loss Plan — What Works in the UK
If you're looking for an immediate weight loss plan, you're not alone. Millions of UK adults want to lose weight effectively and safely. The good news is there are proven methods available—from lifestyle changes to prescription medications—but it's important to understand what actually works. The NHS recommends a structured, sustainable approach rather than crash diets. This guide covers evidence-based strategies, weight management options, and how to get started with a realistic plan that fits your life.
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 and Effective Weight Loss Strategies
The NHS recommends losing weight at a rate of 0.5 to 1 kg per week for sustainable, healthy results. Faster weight loss often leads to muscle loss and is harder to maintain. Here are proven approaches:
- Calorie deficit: A reduction of around 500 kcal per day typically results in approximately 0.5 kg per week loss. Use our free BMI calculator and weight converter to understand your current baseline and target healthy weight range.
- Structured diet: Mediterranean diet, low-calorie approaches, or intermittent fasting (16:8 or 5:2) all have evidence supporting modest weight loss alongside increased physical activity.
- Prescription medication: For UK adults with a BMI of 30 or above (or 27 with weight-related health conditions), prescription weight loss injections like Wegovy (semaglutide) or Mounjaro (tirzepatide) may be appropriate following clinical assessment. In clinical trials, GLP-1 weight loss medications helped participants lose an average of 15–20% of body weight, though individual results vary.
- NHS Weight Loss Programme: Free tier 1 support available through your GP, including digital tools and community programmes.
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.
Getting Started With Your Plan Today
Before starting any weight loss plan, check your starting point. Calculate your BMI using our free BMI calculator to understand your current health category according to NHS guidelines. If you're interested in prescription weight loss medication, try our GLP-1 weight loss calculator to estimate potential results at different doses—this can help you have an informed conversation with your GP.
The most important step is consistency, not speed. Whether you choose lifestyle changes, prescription medication, or a combination, success comes from sustainable habits. If eligible for NHS weight management services, ask your GP for a referral to your local tier 3 specialist service. Private online prescribing is also available for prescription weight loss injections. Log your progress using our free progress tracker to stay motivated and identify what works best for you.
- 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 the safest immediate weight loss rate?
The NHS recommends losing 0.5 to 1 kg (1 to 2 lbs) per week. Faster loss increases the risk of muscle loss, nutritional deficiency, and weight regain. Sustainable weight loss requires both dietary changes and increased physical activity—crash diets rarely work long-term.
Can I get prescription weight loss medication on the NHS?
Yes, if eligible. GLP-1 medications like Wegovy (semaglutide) and Mounjaro (tirzepatide) are available through NHS specialist tier 3 weight management services for adults with BMI 30+ or BMI 27+ with weight-related health conditions. Availability varies by region. Your GP can refer you.
How much weight can prescription weight loss injections help me lose?
In clinical trials, Wegovy (semaglutide) helped participants lose approximately 15% of body weight on average, whilst Mounjaro (tirzepatide) showed average losses of 15–21% of body weight. These results were achieved alongside reduced-calorie diet and increased physical activity. Individual results vary significantly.
What's the difference between Wegovy and Ozempic?
Both contain semaglutide, but Wegovy is licensed in the UK specifically for weight management, whilst Ozempic is licensed for type 2 diabetes. Ozempic is not approved for weight loss in the UK—using it for weight loss is off-label. Wegovy is the appropriate licensed weight management version.
Should I try diet and exercise first, or can I use medication immediately?
Most GPs recommend trying lifestyle changes first—diet, physical activity, and behaviour change support. If these haven't worked, or your BMI and health conditions meet eligibility criteria, prescription weight loss medication may be offered as part of a comprehensive plan, not as a replacement for lifestyle 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.