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
What Does a BMI of 27.5 Mean?
A BMI of 27.5 places you in the overweight category according to NHS guidelines. This means your weight is above the healthy range for your height, but it's important to understand what this means for your health and what support is available. The NHS provides clear guidance on weight categories and offers practical pathways to help you manage your weight effectively. Using our free BMI calculator, you can check your personal BMI instantly and see where you fall within the NHS categories.
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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.
NHS BMI Categories and What They Mean
The NHS BMI formula divides adults into clear weight categories based on the ratio of weight to height squared. A BMI of 27.5 falls in the overweight category (BMI 25.0–29.9), which is above the healthy BMI range of 18.5–24.9 but below obesity thresholds.
- Healthy weight: BMI 18.5–24.9
- Overweight: BMI 25.0–29.9 (your range)
- Obese Class I: BMI 30.0–34.9
- Obese Class II: BMI 35.0–39.9
- Severely obese: BMI 40.0+
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds due to higher health risks at lower weights. In these groups, a BMI of 27.5 may indicate a greater health concern and warrants discussion with your GP.
It's important to remember that BMI limitations exist — BMI does not distinguish between muscle and fat, so athletes or very muscular individuals may have a higher BMI without excess body fat. Your GP can assess your individual health picture beyond BMI alone.
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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 Weight Management Pathway and When to Seek Help
If your BMI is 27.5 and you have weight-related health conditions (such as type 2 diabetes, high blood pressure, or sleep apnoea), the NHS may recommend intervention. Your GP can refer you to tier 1 or tier 2 weight management services, which typically include digital tools, community programmes, and behaviour change support.
For more intensive support, specialist tier 3 weight management services offer multidisciplinary assessment and may prescribe weight loss medication if appropriate. The NHS also recommends lifestyle changes: aim for a calorie deficit of 500 kcal per day for sustainable weight loss of approximately 0.5 kg per week. Even a 5–10% reduction in body weight can improve blood pressure, blood sugar control, and reduce health risks significantly. Discuss your options with your GP to create a personalised plan.
- 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.
Is a BMI of 27.5 considered overweight or obese?
A BMI of 27.5 is in the overweight category according to NHS guidelines (BMI 25.0–29.9), not obese. Obesity starts at BMI 30.0. However, if you're from a South Asian, Chinese, Black African, or Black Caribbean background, your GP may advise differently due to higher health risks at lower BMI levels.
What health risks are associated with a BMI of 27.5?
A BMI of 27.5 increases your risk of type 2 diabetes, high blood pressure, cardiovascular disease, and certain cancers compared to a healthy BMI. However, the actual risk depends on other factors including age, genetics, waist circumference, and existing health conditions. Your GP can assess your individual risk.
How much weight do I need to lose to reach a healthy BMI?
This depends on your height. Use our free weight converter and BMI calculator to see your target weight range. For most adults, losing 5–10% of body weight can significantly reduce health risks. Your GP or a weight management service can help create a realistic plan tailored to your circumstances.
Can I get help from the NHS if my BMI is 27.5?
If your BMI is 27.5 and you have weight-related health conditions (diabetes, high blood pressure, sleep apnoea), your GP can refer you to NHS weight management services. These range from digital programmes (tier 1) to specialist services offering medication and support (tier 3). Availability varies by region.
What are the limitations of BMI as a health measure?
BMI does not account for muscle mass, bone density, or where fat is stored on your body. Athletes or very muscular people may have a high BMI without excess body fat. BMI is a useful screening tool, but your GP should consider your overall health picture, waist circumference, and medical history for a complete assessment.
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.