In a nutshell: Research suggests it’s safe for you to lose around 1lb per week of weight while breastfeeding, and diet programmes like Weight Watchers and Slimming World have specially-designed diets for nursing mums. But you’ll burn around 500 calories per day breastfeeding anyway, and our family GP Dr Philippa Kaye doesn’t think dieting while breastfeeding is a good idea, saying:

I would not recommend dieting while breastfeeding - you need to ensure good nutrition and especially hydration during feeding in order to create enough milk.

How many calories does breastfeeding burn?

It’s generally accepted that breastfeeding burns around 400 to 500 calories per day and that this is how much extra you’ll need when breastfeeding - as Dr Philippa says: "During breastfeeding you need to have 500kcal a day extra."

Though she also notes: "However, you have been laying down fat during pregnancy to help you come up with this extra energy."

The 400 to 500-calories stat is backed up by the American College of Obstetricians and Gynaecologists, too, who advise that breastfeeding women need 450 to 500 extra calories when breastfeeding - around 2,500 a day in total, and certainly not less than 1,800.

Is it safe to diet when breastfeeding?

If you’re worried about whether dieting while breastfeeding will affect the quality and / or quantity of your milk and, in turn, your baby – it really depends on how much weight you’re losing.

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A 1998 study from the University of California, looking at the effects of restricted calories during breastfeeding, showed that losing 2kg or less per month had no adverse effects on milk composition or volume 1, as long as the mum wasn’t undernourished and was feeding her baby on demand.

International board certified lactation consultant Kelly Bonyata, founder of parenting / breastfeeding website Kellymom, sites this stat, and La Leche League says it’s safe to lose 1lb a week - based figures in a book, Counseling The Nursing Mother, by IBCLCs Judith Lauwers and Anna Swisher.

Kelly also advises that any sudden weight loss can lead to a drop in milk supply, though.

How soon can I start dieting if I’m breastfeeding?

Most advice we’ve seen from those in the know - including La Leche League GB and Kellymom - says you should wait until around 6 to 8 weeks, when your milk supply is established, before thinking of dieting.

Above all things, it’s important to give yourself time to heal from birth, and to put your happiness first and the wellbeing of your baby before anything else. And if you really do want to diet, don’t be too harsh on yourself. As Dr Philippa advises:

Remember - it took you 9 months to gain the weight so it is going to take some time to lose it! Enjoy the time feeding your baby if possible, try to eat healthily - but I would recommend a restrictive diet during feeding.

Can I join Slimming World or Weight Watchers when breastfeeding?

We know some of the mums on our forum do use diets like Weight Watchers and Slimming World when breastfeeding.

And, from what we can gather, these kinds of programmes say you can take part in them if you’re breastfeeding and they should tailor their systems if they know you are doing so - just be sure to tell them if you are.

Mum porkchop - a former Weight Watchers leader - on our forum says: "I used to do Weight Watchers, worked better for me than Slimming World, but were all different.

"Weight Watchers is a counting points system, and you get extra points per day for breastfeeding - the number depends if you are exclusively or mix feeding."

We would say though, based on what Dr Philippa’s advised, it might be worth checking in with your GP before starting such a diet if you’re breastfeeding.

Will breastfeeding alone help me lose weight?

As we’ve seen, you burn around 500 calories while breastfeeding, and there is some evidence that breastfeeding can help you lose weight.

A 2014 study, looking at the effects of breastfeeding on postpartum weight loss among US women 2, suggested:

"Women who breastfed exclusively for at least 3 months had a 1.3-pound… greater weight loss at 6 months postpartum, relative to those who did not breastfed or breastfed non-exclusively.

"At 9 months postpartum, exclusive breastfeeding for at least 3 months led to a 3.7-pound… greater postpartum weight loss, relative to non-exclusive or no breastfeeding.”

And Dr Philippa comments: "If you are eating a healthy diet, breastfeeding can actually help you lose weight."

But it’s not guaranteed that the extra calories you use when breastfeeding will necessarily mean the weight falls off. As Kelskiii on our forum found: "I was expecting this huge weight loss that everyone goes on about...

"I've lost a stone when R was born then bopped up & down 5lb!! I joined Slimming World and lost nothing, not sure if I was eating too much?"

And mummysimpson found the same, saying: "Honestly, I feel like I haven't lost any weight breastfeeding. Others say differently.

"When I did start trying to calorie count and I did start losing weight it actually affected my milk supply which was very stressful.

"So I went back to eating "normally" again and my milk supply went back to normal - I have been a lot happier since."

As we see from these mums, weight loss isn’t inevitable when breastfeeding.

When you’re breastfeeding, you may find you’re exhausted through disrupted sleep, and so jump at a sugary snack more readily than you usually would.

Additionally, if you have a young baby to look after you may possibly (though not necessarily) find yourself leading a more sedentary, stay-at-home life - all of which could mean the weight doesn’t necessarily fall off quickly.

Diet while breastfeeding: what should you eat?

The most important thing to remember when you’re breastfeeding is that you need to have a balanced diet – the NHS has guidelines on what to eat which are basically the same as for adults generally – see their guidelines for a health breastfeeding diet if you’re unsure.

Exercising when breastfeeding

Another way to help lose weight if you want to, other than dieting, is to exercise. Even if you’ve had a c-section, getting up and about is a good idea, though in the first week or so this should mean simply gentle walks and not going too far.

Whether you had a c-section or a vaginal birth you might find that your post-partum bleeding increases if you overdo it - so simply slow down and take it easy again for a few weeks.

Your 6-week check-up is a good point at which to see how your body is doing and if you are ready for formal exercise yet. At first try walking.

Discuss gym exercising with your doctor before you go back to anything more strenuous as she will be aware of your own birth experience and body state.

While you are breastfeeding, keeping up your liquids is important all the time, so make especially sure that you are drinking enough water when exercising.

If you get breast problems like mastitis make sure you stop doing any exercising which might exacerbate the problem. Consult your doctor or health visitor, or your gym instructor if you’re not sure.

Pics: Getty


1. Effects of Maternal Caloric Restriction and Exercise during Lactation, The Journal of Nutrition, Volume 128, Issue 2, February 199, Katherine G. Dewey et al. DOI: 10.1093/jn/128.2.386S

2. Effects of breastfeeding on postpartum weight loss among U.S. women, Prev Med, 2014 Dec, Marian P. Jarlenski et al.


About our expert GP Philippa Kaye

Dr Philippa Kaye works as a GP in both NHS and private practice. She attended Downing College, Cambridge, then took medical studies at Guy's, King's and St Thomas's medical schools in London, training in paediatrics, gynaecology, care of the elderly, acute medicine, psychiatry and general practice. Dr Philippa has also written a number of books, including ones on child health, diabetes in childhood and adolescence. She is a mum of 3.

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Tara BreathnachContent Editor and Social Media Producer

Tara is mum to 1 daughter, Bodhi Rae, and has worked as Content Editor and Social Media Producer at MadeForMums since 2015