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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Thyroid Diet Plan for Weight Loss — UK Medication Options
If you have a thyroid condition and struggle with weight management, you may be wondering whether a thyroid diet plan alone is enough. While diet does play an important role, prescription weight loss medication is now available in the UK for eligible adults with a BMI of 30 or above, or 27 and above with weight-related health conditions. This guide explores how thyroid health, nutrition, and medical weight management options work together to support sustainable weight loss in the UK.
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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.
UK-Licensed Prescription Weight Loss Medications
If you're looking for weight management uk support beyond diet, three prescription weight loss injections are currently licensed in the UK: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide).
Mounjaro is a once-weekly injection that works as a dual GIP and GLP-1 receptor agonist. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks alongside a reduced-calorie diet and physical activity.
Wegovy is also a once-weekly injection and a GLP-1 receptor agonist. In clinical trials, participants achieved approximately 15% average body weight loss.
Saxenda is a daily injection and the oldest GLP-1 option available in the UK. All three are prescription-only medicines and require a clinical assessment before being prescribed. Individual results vary significantly, and these medications work best alongside lifestyle changes, not instead of them.
Clinically BackedWeight Loss
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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
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
NHS vs Private Access — How to Start
In the UK, nhs weight loss medication is available through specialist tier 3 weight management services. Your GP can refer you, though waiting lists vary significantly by region and may be lengthy. Private prescription weight loss is also available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber — you do not need an NHS referral.
Before exploring medication, check your eligibility using our free BMI calculator above. If your BMI suggests you may be eligible, discuss your options with your GP or a licensed prescriber. They will assess your individual health, any thyroid medication interactions, and whether weight loss injections uk are appropriate for you. Even if you choose not to pursue medication, professional support significantly improves weight loss success rates.
- 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 take weight loss injections if I have a thyroid condition?
Possibly, but this requires individual assessment. Weight loss injections do not directly affect thyroid function, but your prescriber needs to know about your thyroid medication and any recent changes. GLP-1 medications may affect how quickly oral medications (including thyroid medication) are absorbed, so dosing adjustments may be needed. Always inform your prescriber of all medications you take.
Will a thyroid diet plan alone help me lose weight?
A thyroid-supportive diet — including adequate iodine, selenium, and zinc — is important for thyroid health and can support weight management. However, if you have a significant BMI or weight-related health conditions, medical support through prescription medication combined with diet often delivers better results than diet alone. Your GP can advise on the best approach for your individual situation.
How much weight can I realistically lose with prescription medication?
Clinical evidence shows average weight loss of 15–21% of body weight with GLP-1 medications over 6–12 months, but individual results vary significantly. Some people lose more, some less. Weight loss is not assured and depends on adherence to lifestyle changes, underlying health conditions, and how your body responds. Our GLP-1 weight loss calculator can help you explore projected ranges.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro showed slightly higher average weight loss in clinical trials (15–21% vs 15%), but both are effective. Saxenda is a daily injection. Your prescriber will recommend the best option based on your health profile and preference.
How do I check if I'm eligible for weight loss medication in the UK?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with at least one weight-related health condition (such as type 2 diabetes, high blood pressure, or heart disease). South Asian, Chinese, Black African, and Black Caribbean adults have slightly lower thresholds. Use our free BMI calculator above to check your BMI, then speak with your GP or a licensed prescriber about your options.
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.