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 During Nursing: What's Safe?
Losing weight whilst breastfeeding is possible, but it requires a careful, gradual approach to protect milk supply and your baby's nutrition. The NHS recommends that nursing mothers should not attempt gradual weight management or restrictive dieting. Instead, a modest calorie deficit combined with balanced nutrition and adequate hydration supports both your health and breastfeeding success. If you're interested in weight management UK strategies, your GP can provide personalised guidance based on your individual circumstances.
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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 While Breastfeeding
The NHS advises that losing no more than 0.5 kg (about 1 lb) per week is safe during breastfeeding. Faster weight loss can reduce milk supply and deprive your baby of essential nutrients. Here's what matters:
- Calorie deficit: Aim for a modest 300–500 kcal daily deficit rather than aggressive restriction. This supports gradual weight loss without compromising milk production.
- Nutrition: Eat balanced meals with adequate protein, healthy fats, and whole grains. Skipping meals or crash dieting risks nutrient deficiency and reduced milk supply.
- Hydration: Drink plenty of water—dehydration directly impacts lactation and can slow weight loss.
- Timing: Wait until breastfeeding is well-established (at least 6–8 weeks postpartum) before actively trying to lose weight.
The NHS weight loss guidance applies during nursing, but the approach should be gentler and more gradual than standard weight management approaches.
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.
Weight Loss Medication and Breastfeeding
Prescription weight loss medications like Wegovy and Mounjaro are not suitable during breastfeeding. Both semaglutide (Wegovy) and tirzepatide (Mounjaro) pass into breast milk in unknown amounts and have not been studied in nursing mothers. The MHRA advises against using these prescription weight loss injections whilst breastfeeding or planning to breastfeed.
If you're considering weight loss medication, you must stop breastfeeding first. Your GP can discuss when it's safe to restart any weight loss medication after you've finished nursing. Focus on NHS weight loss strategies—balanced eating, gradual calorie deficit, and physical activity—until breastfeeding ends.
- 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 use my BMI to guide weight loss whilst nursing?
Yes. Use our free BMI calculator to check your current BMI and healthy weight range. However, remember that weight loss targets should be gradual (0.5 kg weekly max) and should never compromise milk supply. Your GP can help set realistic weight targets for your nursing period.
When is it safe to start trying to lose weight after birth?
The NHS recommends waiting until breastfeeding is well-established, typically 6–8 weeks postpartum. Before this, focus on recovery and feeding. After 8 weeks, you can begin gentle calorie reduction (300–500 kcal daily deficit) alongside balanced nutrition and adequate hydration.
Will losing weight affect my milk supply?
Gradual weight loss (0.5 kg weekly) alongside good nutrition and hydration should not harm milk supply. gradual weight management, skipped meals, or very restrictive dieting can reduce supply. If you notice changes in milk production, speak to your GP or health visitor immediately.
Can I use prescription weight loss injections while breastfeeding?
No. Wegovy, Mounjaro, and other prescription weight loss medications are not recommended during breastfeeding as they pass into breast milk. You must stop breastfeeding before starting these medications. Your GP can advise on the safest timing.
What's the best approach to lose weight during nursing?
Combine a modest calorie deficit (300–500 kcal daily), balanced meals with adequate protein and healthy fats, plenty of water, and gentle physical activity. Track your progress with our free progress tracker to monitor weight changes alongside milk supply observations. Always consult your GP or health visitor if you have concerns.
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.