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 — What's Safe?
Losing weight while breastfeeding is possible, but it requires a careful, health-focused approach to protect both your milk supply and your baby's nutrition. Most UK health professionals recommend waiting at least 6–12 weeks after birth before actively trying to lose weight, as your body needs this time to establish milk production. If you're considering weight management during nursing, your GP can provide personalised guidance on safe dietary changes, exercise, and whether prescription weight loss medication is appropriate for you at this time.
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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.
Safe Weight Loss During Breastfeeding
The NHS advises that breastfeeding itself burns approximately 300–500 kcal per day, which can naturally support gradual weight loss without restrictive dieting. However, severe calorie restriction or gradual weight management can reduce milk supply and affect milk quality, potentially impacting your baby's nutrition and development.
- Timing matters: Wait 6–12 weeks after birth before intentional weight loss to establish milk supply
- Gradual approach: Aim for no more than 0.5 kg per week loss — faster weight loss risks depleting nutrient stores
- Nutrition is critical: You need adequate protein, calcium, iron, and B vitamins to support both milk production and your own health recovery
- Hydration: Breastfeeding increases fluid needs — drink water regularly throughout the day
- Avoid crash diets: Very low calorie diets (under 1,800 kcal daily) are not recommended during nursing
Always check with your GP before starting any weight loss plan, calorie-controlled diet, or new exercise programme while breastfeeding. Your GP can assess your individual recovery and health needs.
Clinically BackedWeight Loss
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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.
Prescription Weight Loss Medication While Breastfeeding
GLP-1 medications (such as Wegovy and Mounjaro) are not recommended during breastfeeding. These prescription weight loss injections have not been studied in breastfeeding women, and their effects on milk supply and infant safety are unknown. If you're considering prescription weight loss medication as part of NHS weight loss or weight management plans, discuss this with your GP or prescriber — they will advise you to wait until you've finished nursing before starting treatment.
The same applies to other prescription weight loss medications. Your prescriber will assess whether treatment is appropriate for you based on your current health status and breastfeeding plans. Non-medication approaches — such as balanced nutrition, gradual calorie reduction, and increased physical activity — are the safest options during nursing.
Breastfeeding itself is a form of physical activity that uses energy. Combined with gentle exercise (like walking) and a nutritionally balanced diet with a modest calorie reduction, gradual weight loss is achievable without medication. Track your weight loss progress safely using healthy tracking methods, and monitor your milk supply — if you notice a drop in production, increase calorie intake immediately and consult your GP or lactation specialist. Remember that post-pregnancy weight loss is a marathon, not a sprint; focusing on nourishment and sustainable habits now will serve you better long-term than rapid loss.
- 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 breastfeed while taking Wegovy or Mounjaro?
No. GLP-1 medications like Wegovy and Mounjaro are not recommended during breastfeeding because they haven't been studied in nursing women. Their effects on milk supply and infant safety are unknown. Speak to your GP or prescriber — they will advise waiting until you've finished nursing before starting weight loss medication.
How much weight loss is safe while breastfeeding?
The NHS recommends no more than 0.5 kg per week. Breastfeeding burns 300–500 kcal daily naturally. gradual weight management or severe calorie restriction can reduce milk supply and deplete your nutrient stores, affecting both your health and your baby's nutrition.
When can I start trying to lose weight after giving birth?
Most health professionals recommend waiting 6–12 weeks after birth before intentionally losing weight. This allows your body to recover and your milk supply to establish. After 6–12 weeks, if you're exclusively breastfeeding and feeling well, you can discuss safe weight loss approaches with your GP.
What nutrients are most important while breastfeeding and losing weight?
Protein, calcium, iron, vitamin D, and B vitamins are critical. Breastfeeding increases your nutritional demands significantly. Never skip meals or nutrients when nursing — eat regular, balanced meals with lean proteins, whole grains, fruits, vegetables, and dairy. Your GP or a registered dietitian can provide personalised nutrition advice.
Is it normal to lose weight naturally while breastfeeding?
Yes. Breastfeeding burns significant calories, and many women lose weight gradually in the months after birth without dieting. However, this varies — some women lose weight quickly, others slowly, and some maintain weight until weaning. This is normal and individual. Focus on health and milk supply rather than gradual weight management.
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.