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 Breastfeeding — Safe Approaches for UK Mums
Losing weight while breastfeeding is possible, but requires a careful, informed approach that protects both milk supply and baby's nutrition. The NHS recommends gradual weight loss for breastfeeding mothers, as gradual weight management can affect milk quality and quantity. Most of the weight gained during pregnancy comes off naturally within the first six months postpartum, even without active weight loss efforts. This guide covers safe NHS weight management approaches, what to avoid, and when to seek GP support for your individual situation.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Safe Weight Loss While Breastfeeding
The NHS advises that breastfeeding mothers should aim for gradual weight loss of no more than 0.5 kg per week (approximately 1 lb per week). Rapid or severe calorie restriction can reduce milk supply and affect milk composition, potentially impacting baby's nutrition.
- Avoid crash diets, very low calorie diets (under 1,800 kcal/day), and extreme dietary changes whilst breastfeeding
- Most mothers naturally lose 0.5–1 kg per month in the first 6 months postpartum from breastfeeding alone
- Breastfeeding itself burns approximately 300–500 kcal per day, supporting gradual weight loss
- Wait at least 2 months postpartum before actively trying to lose weight — this gives milk supply time to establish
- Speak to your GP or health visitor before starting any formal weight loss programme
Using our free BMI calculator can help track whether your current weight falls within a healthy range for your height, but remember that postpartum weight loss is gradual and normal.
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.
Medications and Prescription Weight Loss During Breastfeeding
Prescription weight loss medications such as GLP-1 injections are not suitable whilst breastfeeding. Medications like semaglutide (Wegovy) and tirzepatide (Mounjaro) have not been studied in breastfeeding women, and their safety for nursing babies is unknown. These medications should only be considered after breastfeeding has completely stopped.
- Stop breastfeeding entirely before starting any prescription weight loss medication
- Discuss timing with your GP if you're considering medication-assisted weight loss — your healthcare team can advise when it's safe to begin
- Hormonal contraceptives can also affect milk supply — check with your GP about safe contraceptive options whilst breastfeeding
For NHS weight management support during breastfeeding, your GP can refer you to community weight management programmes designed specifically for postpartum mothers.
- 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 diet while breastfeeding?
Yes, but carefully. The NHS recommends gradual weight loss (no more than 0.5 kg per week) and avoiding very low calorie diets. Focus on balanced meals with plenty of water, fruits, vegetables, and whole grains. Sudden or severe calorie restriction can reduce milk supply and affect milk quality.
When can I start losing weight after giving birth?
Wait at least 2 months postpartum to allow milk supply to fully establish. Most mothers naturally lose weight during this period from breastfeeding alone. After 2 months, gradual active weight loss is safe if done carefully alongside continued breastfeeding.
Is Wegovy or Mounjaro safe while breastfeeding?
No. GLP-1 and GIP/GLP-1 weight loss medications have not been studied in breastfeeding women and are not recommended. These prescription medications should only be considered after breastfeeding has completely stopped. Always discuss with your GP.
How many calories should I eat while breastfeeding?
Most breastfeeding mothers need approximately 2,000–2,500 kcal per day, depending on activity level and pre-pregnancy weight. Breastfeeding burns 300–500 kcal daily naturally. Never eat fewer than 1,800 kcal per day whilst nursing. Your GP or a dietitian can give personalised guidance.
What's the safest way to manage weight loss while breastfeeding?
Combine gentle dietary changes (balanced meals, adequate hydration), regular physical activity (walking, postnatal exercises once cleared by GP), and patience. Most mothers lose 0.5–1 kg per month naturally. Track your weight using our free progress tracker, and speak to your health visitor or GP if you have concerns about milk supply or weight loss speed.
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.