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 Tips for UK Adults
If you're looking to lose weight quickly, there are several evidence-based steps you can take right now. The most effective immediate actions include creating a calorie deficit, increasing physical activity, and drinking more water — all of which can produce noticeable results within days or weeks. For longer-term success, combining these lifestyle changes with professional support through NHS weight management services or prescription weight loss medication may help. This guide covers practical tips you can start today, plus information about medical options available across the UK.
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.
Quick Actions You Can Start Today
Create a calorie deficit: Eating 500 calories fewer than your body needs daily typically results in losing around 0.5 kg per week — the NHS-recommended safe rate. Start by tracking food intake using a free app or food diary to understand your baseline.
Increase water intake: Drinking water before meals can help you feel fuller, reducing overall calorie intake. Aim for 6–8 glasses daily and swap sugary drinks for water immediately.
Move more: Even 30 minutes of brisk walking daily increases energy expenditure. Physical activity supports both weight loss and cardiovascular health.
Reduce processed foods: Cutting ultra-processed foods and choosing whole foods (vegetables, lean proteins, whole grains) naturally reduces calorie density and increases satiety.
Check your BMI: Use our free BMI calculator to establish your current weight category and set a realistic healthy weight range for your height — this helps create a personalised target.
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.
When to Consider Medical Support
If lifestyle changes alone aren't delivering results, or you've struggled with weight management before, prescription weight loss medication may help. In the UK, options include GLP-1 weight loss injections (such as Wegovy or Mounjaro) or referral to NHS weight loss services. These prescription medications work alongside diet and exercise — not instead of them.
Access through the NHS requires referral to a specialist tier 3 weight management service from your GP. Private prescribing is also available following an online clinical assessment with a licensed prescriber. Our GLP-1 weight loss calculator can help you estimate potential results at different medication doses, giving you a realistic picture of what to expect.
- 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 lose in a week?
The NHS recommends losing 0.5–1 kg per week for sustainable, healthy weight loss. Losing more than this increases muscle loss and metabolic risk. Rapid initial weight loss (often from water and glycogen depletion) may occur in the first 1–2 weeks on a diet, but this slows after that.
What's the fastest safe way to lose weight?
Creating a 500–750 kcal daily deficit through diet and exercise is the fastest safe approach. This typically results in 0.5–1 kg loss weekly. For faster results, a low-calorie diet (800–1200 kcal/day) should only be followed under GP supervision.
Can prescription weight loss medication help with immediate results?
Yes. Clinical trials show GLP-1 medications like Wegovy may help achieve clinically studied weight loss on average, though individual results vary. Results develop over weeks and months, not days. These medications are prescription-only and require clinical assessment before use.
Do I need a GP referral for weight loss medication?
For NHS access, yes — your GP refers you to specialist services. For private prescribing, no — you can access a licensed prescriber online, though eligibility is still assessed individually. Either way, a clinical assessment is required.
What's the best way to track my weight loss progress?
Weigh yourself once weekly at the same time and use our free progress tracker to log results. Avoid daily weigh-ins (weight fluctuates naturally). Track non-scale progress too: energy levels, how clothes fit, and how you feel physically.
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.