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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Kidney Disease and Weight Loss — What You Need to Know
If you have kidney disease, managing your weight safely is important for your overall health, but it requires careful consideration and medical guidance. Excess weight can put additional strain on your kidneys and increase risk of complications like high blood pressure and diabetes. However, weight loss approaches must be tailored to your kidney function and overall health status. This guide explains what you need to know about weight management with kidney disease, including when prescription weight loss medication might be appropriate and how to work with your healthcare team.
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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.
Weight Loss and Kidney Health — Key Considerations
People with kidney disease face specific challenges when attempting weight loss. Your kidneys filter waste products and excess fluid from your blood, so their function directly affects how your body processes nutrients, medications, and weight loss interventions. A modest weight loss of just 5–10% of your body weight can meaningfully reduce blood pressure and ease strain on your kidneys, but the approach must be personalised to your kidney stage and overall health.
- Early-stage kidney disease (stages 1–2): More weight loss flexibility, but still requires GP guidance
- Moderate kidney disease (stage 3): Weight loss is beneficial but dietary protein, sodium, and potassium intake become critical
- Advanced kidney disease (stages 4–5): Weight management becomes more complex and requires specialist renal dietitian input
The NHS recommends working with your renal team before starting any structured weight loss plan. Your GP or kidney specialist can assess your kidney function, medications, and individual risk factors to create a safe approach tailored to your needs.
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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
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Weight Loss Medication and Kidney Disease
If you are considering prescription weight loss medication such as GLP-1 injections (including Wegovy or Mounjaro), your kidney function must be assessed carefully beforehand. These medications may require dose adjustment or careful monitoring if your kidney function is reduced. Some people with kidney disease may still be eligible for weight loss medication, but this depends on your individual kidney stage, other health conditions, and your medications.
Your prescriber will assess your kidney function through blood tests (eGFR and creatinine levels) before issuing any prescription. Always inform your healthcare team of your kidney disease diagnosis — it is essential information for safe prescribing. Work with your GP or renal specialist and the prescriber together to confirm that weight loss medication is appropriate for you and that your kidney health will be monitored throughout.
- 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 lose weight safely if I have kidney disease?
Yes, but with careful medical guidance. Weight loss can reduce blood pressure and ease kidney strain. However, your approach must be tailored to your kidney stage, dietary restrictions, and medications. Always work with your GP or renal specialist before starting any weight loss plan. A modest 5–clinically studied weight loss often brings meaningful health benefits.
Are weight loss injections safe if I have kidney disease?
Weight loss medications like GLP-1 injections may be an option for some people with kidney disease, but your kidney function must be assessed first. These medications may need dose adjustment depending on your kidney stage. Your prescriber will check your kidney function through blood tests (eGFR) before prescribing. Always disclose your kidney disease diagnosis to any healthcare provider.
What dietary changes should I make for weight loss with kidney disease?
Dietary needs vary significantly depending on your kidney stage. Early-stage kidney disease may allow standard healthy eating, but advanced stages often require limits on protein, potassium, phosphorus, and sodium. A renal dietitian can create a safe, personalised plan. Your GP can refer you to specialist dietitian support through the NHS.
How often should my kidney function be monitored during weight loss?
Your GP or renal team will recommend a monitoring schedule based on your kidney stage and treatments. Regular blood tests (eGFR, creatinine) are standard. If you start prescription weight loss medication, monitoring may increase initially. Ask your healthcare team how often you need check-ups.
Should I use a BMI calculator if I have kidney disease?
BMI can be a useful screening tool, but it has limitations — it doesn't account for muscle mass or where fat is stored. With kidney disease, your overall health picture is more complex. Use a BMI calculator as a reference point, but rely on your GP or renal specialist's personalised assessment for safe weight management guidance specific to your kidney health.
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.