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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DNA Weight Loss Calculators — What the Science Actually Shows
DNA weight loss calculators claim to predict how much weight you'll lose based on your genetic makeup, but the science is more complicated than the marketing suggests. While genetics do play a role in weight management, a DNA test cannot reliably forecast your personal weight loss results. In the UK, evidence-based approaches to weight management focus on proven methods: calorie deficit, lifestyle changes, and when appropriate, prescription weight loss medication assessed by your GP. This guide explains what DNA calculators claim, what research actually shows, and which tools genuinely help with 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.
What DNA Weight Loss Calculators Claim to Do
DNA weight loss calculators typically analyse your genetic variants to predict how your body responds to diet, exercise, and metabolism. They claim to tell you your "genetic weight loss potential" or estimate how much weight you might lose following their recommended plan.
- They test for genes related to appetite, fat storage, and calorie burning
- They often recommend personalised diet types (low-carb, low-fat, Mediterranean)
- Some integrate with fitness apps or weight tracking
- Marketing often suggests this is more accurate than standard weight loss prediction
The appeal is clear: a personalised roadmap based on your unique genetics sounds scientific and promising. However, genetic testing for weight loss is not currently recommended by the NHS, and individual results vary dramatically—not because of genetics alone, but because weight loss depends on far more than DNA. Actual weight management in the UK relies on proven methods like creating a calorie deficit through reduced-calorie diet and increased physical activity, with support from your GP where needed.
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.
Why Genetics Alone Don't Predict Weight Loss
Genetics influence metabolism, hunger hormones, and how your body stores fat—but they account for only about 30–40% of weight variation. The other 60–70% depends on diet, physical activity, sleep, stress, medications, and medical conditions. A DNA test cannot capture these factors.
- Twin studies show identical genetics with very different weight outcomes based on lifestyle
- A gene variant might slightly increase appetite, but willpower, food availability, and stress matter far more
- Environmental and behavioural factors change constantly; genes do not
- No genetic test can predict your individual response to a specific diet or exercise plan
If you want genuine weight loss support in the UK, use our free BMI calculator to understand your current health context, track progress with our progress tracker, and speak to your GP about evidence-based options—including NHS weight management services or, if eligible, prescription weight loss medication like Mounjaro or Wegovy, which are assessed on an individual clinical basis.
- 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 a DNA test tell me how much weight I'll lose?
No. DNA tests can identify genetic variants that influence appetite and metabolism, but they cannot predict your individual weight loss outcome. Weight loss depends on calorie deficit, lifestyle, stress, sleep, and behaviour—factors DNA cannot measure. The NHS recommends focusing on proven methods: reduced-calorie diet, physical activity, and support from your GP.
Is DNA weight loss testing available on the NHS?
No. Genetic testing for weight loss prediction is not currently recommended or funded by the NHS. The NHS weight management pathway focuses on behaviour change, dietary support, and when appropriate, prescription weight loss medication—all assessed by your GP without genetic testing.
Are DNA weight loss calculators more accurate than standard calculators?
No. Standard calculators based on your current BMI, height, weight, age, and activity level are often more reliable than genetic predictions. Our free BMI calculator and GLP-1 weight loss calculator use evidence-based formulas and are more practical for understanding your personal weight management context.
What actually works for weight loss in the UK?
Evidence supports: consistent calorie deficit (aim for 0.5–1 kg loss per week), regular physical activity, adequate sleep, and stress management. If you have a BMI over 30 or 27 with weight-related health conditions, your GP can refer you to NHS specialist services or discuss prescription weight loss medication like Mounjaro or Wegovy.
Should I spend money on a DNA weight loss test?
Spending on DNA weight loss tests is unlikely to improve your results. Instead, invest time in understanding your BMI using our free calculator, tracking your progress, and speaking with your GP about proven weight management approaches suited to your individual 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.