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
Weight Loss While Nursing Breastfeeding — UK Guide
Losing weight while breastfeeding requires careful consideration to maintain milk supply and ensure your baby gets adequate nutrition. In the UK, the NHS recommends a gradual approach to postpartum weight loss, typically no more than 0.5–1 kg per week. Most prescription weight management options are not suitable during breastfeeding, but your GP can discuss safe alternatives including dietary changes, increased physical activity, and specialist support through NHS weight management services. Always speak to your health visitor or GP before starting any weight loss programme while nursing.
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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.
Prescription Weight Loss Options While Breastfeeding
Most prescription weight loss medications available in the UK—including Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide)—are not recommended while breastfeeding. These GLP-1 receptor agonists have not been adequately studied in nursing mothers, and safety data for infants is limited. The manufacturers advise against use during breastfeeding. However, this does not mean you cannot access NHS weight management support. Your GP can refer you to tier 2 or tier 3 NHS weight management services, which offer evidence-based dietary guidance, behaviour change programmes, and exercise support tailored to breastfeeding mothers. These services assess your individual circumstances and provide safe, practical weight loss strategies that protect milk supply. If you have weight-related health conditions such as type 2 diabetes or high blood pressure, your GP may discuss medication options once breastfeeding has stopped.
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.
NHS Support and When to Seek Help
The NHS recommends gradual weight loss during and after breastfeeding. Your health visitor or GP can signpost you to NHS weight loss programmes designed for postpartum women, which typically combine nutrition guidance, physical activity, and psychological support. Crash dieting, very low-calorie diets, or gradual weight management can reduce milk supply and may mobilise environmental contaminants stored in body fat—potentially affecting breast milk quality. If you are overweight or obese (BMI over 25 or 30, depending on ethnicity), discuss a personalised weight loss plan with your GP before starting any intervention. Once you have stopped breastfeeding, your GP can reassess you for prescription weight management options if eligible based on your BMI and health conditions. Use our free BMI calculator to check your current BMI, and consider our weight converter to track progress in familiar units (stone, lbs, or kg).
- 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 while breastfeeding?
No. Mounjaro (tirzepatide) and Wegovy (semaglutide) are not recommended during breastfeeding due to insufficient safety data in nursing mothers. Both manufacturers advise against use. Speak to your GP about safe alternatives, such as NHS weight management programmes, once breastfeeding has stopped.
What is a safe rate of weight loss while nursing?
The NHS recommends losing no more than 0.5–1 kg per week while breastfeeding. gradual weight management can reduce milk supply and may release stored contaminants into breast milk. Gradual, sustainable changes to diet and activity are safer for both you and your baby.
Can I access NHS weight management services while breastfeeding?
Yes. Your GP can refer you to tier 2 (primary care) or tier 3 (specialist) NHS weight management services. These offer nutrition guidance, physical activity support, and behaviour change programmes designed for postpartum women and are safe while breastfeeding.
When can I start prescription weight loss medication after weaning?
Once you have fully stopped breastfeeding, your GP can reassess your eligibility for prescription weight loss treatment based on your BMI and health conditions. There is no standard waiting period, but discuss the timing with your GP or healthcare professional.
What should I eat to lose weight safely while breastfeeding?
Avoid crash diets or very low-calorie diets, which can reduce milk supply. Aim for a modest calorie deficit (around 300–500 kcal/day), prioritise nutrient-dense foods, stay well-hydrated, and ensure adequate protein and healthy fats. Your health visitor or GP can refer you to a dietitian for personalised guidance.
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.