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
Is Weight Loss Safe During Pregnancy?
Weight loss during pregnancy is not recommended for most women, as your body needs adequate nutrition to support your baby's development. However, weight management remains important for maternal health. If you're concerned about your weight or have been gaining weight rapidly, your GP or midwife can provide personalised guidance. This guide explains NHS recommendations for safe weight management during pregnancy, including why prescription weight loss medications are not suitable, and how to discuss your individual situation with your healthcare team.
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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.
Weight Management and Medication During Pregnancy
Prescription weight loss medications are not suitable during pregnancy. Mounjaro (tirzepatide), Wegovy (semaglutide), and other GLP-1 weight loss injections are prescription-only medicines that must not be used during pregnancy or if you are planning to become pregnant. These medications have not been adequately studied in pregnancy and may pose risks to your developing baby.
If you are currently taking any prescription weight loss medication and discover you are pregnant, contact your GP or midwife immediately—do not stop taking medication without medical guidance, but your prescriber will assess whether it should be continued, changed, or stopped based on your individual circumstances.
Weight management in the UK is normally approached through dietary adjustments and increased physical activity under NHS guidance, rather than medication during pregnancy. Your midwife and GP are the best sources for safe, evidence-based weight management advice tailored to your pregnancy.
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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.
Discussing Weight and Pregnancy With Your Healthcare Team
The NHS recommends discussing any weight concerns with your GP or midwife at your antenatal appointments. They can assess your individual health needs, monitor your weight gain pattern, and provide safe, evidence-based advice on nhs weight loss approaches that don't compromise your baby's nutrition.
If you were considering prescription weight management before discovering you were pregnant, your GP can discuss safer alternatives and when you might be able to revisit medication options after pregnancy and breastfeeding (if applicable). Weight management UK resources and your local maternity services can also provide practical support for healthy eating and safe exercise during pregnancy. Your healthcare team will help you make the best decisions for both you and your baby's health.
- 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 Mounjaro or Wegovy if I'm pregnant?
No. Mounjaro (tirzepatide) and Wegovy (semaglutide) must not be used during pregnancy. These prescription-only weight loss medications have not been adequately studied in pregnancy and should be stopped before conception or immediately if pregnancy is discovered. Always inform your GP or prescriber if you become pregnant while taking these medications.
Is it safe to lose weight during pregnancy?
Weight loss is generally not recommended during pregnancy, as your body requires adequate nutrition for your baby's development. However, weight gain should be monitored, and your midwife can provide safe weight management guidance. Most women should gain 11–16 kg during pregnancy, though this varies based on pre-pregnancy BMI and individual health factors.
What should I do if I'm already taking weight loss medication and become pregnant?
Contact your GP or midwife immediately if you discover you are pregnant while taking any prescription weight loss medication. Do not stop medication without medical advice—your healthcare team will assess the safest course of action for your individual situation and may change or discontinue medication based on pregnancy-related guidance.
When can I use weight loss medication again after pregnancy?
This depends on your individual circumstances and whether you plan to breastfeed. Mounjaro and Wegovy are not recommended during breastfeeding. Your GP can discuss when it may be safe to restart weight management medication after pregnancy. This is typically discussed at your postnatal review, usually around 6–8 weeks after birth.
What are safe ways to manage my weight during pregnancy?
Your midwife and GP can recommend safe dietary adjustments and appropriate physical activity during pregnancy. The NHS provides free pregnancy and weight management guidance. Eating a balanced diet with adequate nutrients, staying active within safe limits, and attending all antenatal appointments help support healthy weight management for both you and your baby throughout pregnancy.
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.