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
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How to Maintain Weight Loss After You've Lost the Weight
Losing weight is a significant achievement, but keeping it off is often the harder part. Many people regain weight within months without a clear maintenance plan. This guide covers evidence-based strategies for sustaining your weight loss long-term, including lifestyle changes, dietary approaches, and prescription weight management options available in the UK through the NHS and private healthcare. Whether you've lost weight through diet and exercise alone or with medical support, understanding how to maintain your new weight is essential for lasting health benefits.
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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.
Prescription Weight Management Options in the UK
For eligible adults in the UK, prescription weight management medications can help maintain weight loss alongside continued lifestyle changes. Three medications are currently licensed for weight management in the UK:
- Mounjaro (tirzepatide) — a once-weekly injection that works as a dual GIP and GLP-1 receptor agonist. Clinical trials showed it helped participants maintain an average weight loss of 15–21% of their body weight when combined with a reduced-calorie diet and physical activity.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection that helped participants in clinical trials maintain approximately clinically studied weight loss at maximum dose.
- Saxenda (liraglutide) — a daily GLP-1 injection, used less commonly than the once-weekly options.
These are prescription-only medicines requiring individual clinical assessment. Eligibility depends on your BMI and whether you have weight-related health conditions. Weight management medications work best alongside sustained dietary changes and increased physical activity — they are not a substitute for lifestyle changes.
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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.
NHS vs Private Access and Getting Started
In the UK, you can access prescription weight loss medication through two routes:
- NHS: Referral to a tier 3 specialist weight management service through your GP. NHS coverage is available in many areas, though waiting lists and availability vary significantly by region (ICB). Access typically requires a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes or high blood pressure.
- Private: Online consultation with a UK-licensed prescriber, available without NHS referral. Private providers assess eligibility and dispense through GPhC-registered pharmacies. This route is typically faster but involves personal cost.
Start by discussing weight maintenance strategies with your GP. Use our free BMI calculator to understand where you sit on the NHS health weight thresholds, and explore whether prescription support might be right for you. Your GP can advise on both NHS and private options available in your area.
- 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.
Can I stop taking weight loss medication once I've reached my target weight?
No — weight loss medications are typically long-term treatments. If you stop, weight regain is common within weeks or months. These medications work by managing appetite and metabolism, so you need to continue them to maintain results. Always discuss stopping medication with your prescriber, as some require gradual dose reduction.
What's the most important thing for maintaining weight loss?
Sustained lifestyle changes are the foundation. This means eating a healthy, reduced-calorie diet and staying physically active long-term. If you've lost weight with medication, continuing the medication (if appropriate) alongside these habits is key. Weight maintenance is an ongoing commitment, not a one-time achievement.
How can I track my weight loss maintenance progress?
Regular weigh-ins help you spot trends early. Try tracking your weight weekly — variations are normal, so look at the trend over 2–4 weeks rather than daily fluctuations. Our free progress tracker on this page lets you log your weight and visualize your maintenance journey over time.
What should I eat to maintain weight loss?
Focus on whole foods, plenty of vegetables, lean protein, and whole grains. Keep portion sizes mindful — even healthy foods can contribute to weight regain if eaten in excess. A balanced diet with adequate protein helps preserve muscle mass during maintenance. Many people find the Mediterranean diet sustainable for long-term weight management.
How often should I check my BMI during weight maintenance?
Monthly checks are reasonable to track whether your weight is stable. Your BMI indicates where you sit on the NHS health weight scale. Use our free BMI calculator monthly to monitor your standing. If your weight creeps up by 2–3 kg, it's easier to address quickly rather than allowing larger regain.
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.