The truth about breastfeeding and exercise

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The truth about breastfeeding and exercise

The truth about breastfeeding and exercise

A must-read for new mums and mums-to-be for breastfeeding and exercise success.


Welcome to the wonderful world of motherhood, babies, breastfeeding and … yes, exercise. Whether you are a fitness junkie just about to start exercising again after childbirth or a new mum entering these unchartered waters for the first time, you can rest assured it is possible to incorporate exercise into your new life, even when breastfeeding, to the benefit of both you and your baby.

Exercise is 100 per cent recommended for new mums, even when breastfeeding. Certainly, you need to make a few tweaks to any previous exercise programs as you recover from your pregnancy and your baby’s birth, but your body will soon rebuild and strengthen with the correct exercises and techniques.

You will probably find no shortage of people offering advice about breastfeeding, and some may even express their concern for your exercise regime too. The truth is breastfeeding and exercise can be entirely compatible.

Let’s dive deeper into some up-to-date research and practical advice on the subject so you can feel confident to hit the gym again.

Exercise and milk supply

As a new mum in the postnatal phase, you will need to avoid high-powered training. It has been found1 that there can be a short-term effect on milk supply after maximal training exercise, so avoid anything too strenuous. 

Monitor your own experience. Each mum’s body responds differently to breastfeeding. If you are experiencing low milk supply, then consider moderating your training levels. Research2 shows that moderate exercise does not affect breast milk supply, breast milk composition, breast milk volume, infant growth or infant development, and it is in no way detrimental to maternal health.

Of course, there may be other factors causing or contributing to low milk supply too. Look further into the many options available for boosting breast milk supply or speak with a lactation consultant for further advice.

Lactic acid in breast milk

Similarly, evidence3,4 shows that lactic acid in breast milk can vary depending on the level of training undertaken. When lactating women train at moderate intensity, there is no increase of lactic acid in their breast milk post-workout, but when they train at 100 per cent, maximal level, lactic acid levels in their breast milk increased. The increased lactic acid usually returns to resting levels about 30 minutes post-workout, but may take up to 90 minutes.

Either way, it is reassuring and encouraging to know that while lactic acid may increase with maximal training, there are no known harmful effects to babies with this increase.

It is yet to be proven that lactic acid changes the taste of breast milk, but your baby will indicate to you very quickly if they don’t like it. If you do notice your baby turn away, be aware that it could be the taste of the salt from the sweat on your skin that your baby is objecting to. The simple fix here is a gentle wipe or clean of the nipple before you feed. Timing your feeding around your workouts will also help.

Lactation and your metabolism

Don’t bank on breastfeeding as your single tool for ‘losing the baby weight’. For women within a healthy weight range, lactation has been shown to promote weight loss to a moderate extent (this excludes women with a BMI over 35)5. A woman’s hormones are yo-yoing during pregnancy, birth and postnatal phases, and these hormones greatly affect how each mother’s body responds to food, exercise, sleep deprivation and stress.

You will hear personal stories from women claiming that “the weight melted away while breastfeeding”, while others swear that “weight-loss kicked in when my baby had weaned”.  The stories that are true and relevant for some women can be quite different for others.

Timing your workouts and baby’s feeds

The best time to offer your baby a feed is just before you start your workout for two important reasons.

First, comfort. There is nothing worse than trying to complete a workout with full or engorged breasts. As well as being uncomfortable during the workout, it may increase pressure through your bra and encourage blocked ducts.

Second, continuity. It can make for a very long workout if you need to stop halfway through because your baby is upset and hungry. Yes, it will happen from time to time anyway, but if your baby has a full belly pre-workout, they are more likely to last the time it takes for you to complete your session.

If you do find you need to stop your program to feed your baby, maintain your workout by sitting with good posture, practicing your pelvic floor exercises and gentle abdominal bracing.

Bra essentials

If in your pre-pregnancy days you ever exercised without a supportive bra and found it really uncomfortable, you need to know that the feeling of discomfort is much worse when you are nursing. It is essential to wear a quality sports bra that will support and protect your breast tissue while you exercise.

However, choose carefully. While breastfeeding, you need a firm-fitting bra to reduce the ‘bounce factor’, but anything too restrictive or too small will put pressure over your breasts and potentially lead to blocked milk ducts. Your breasts may change sizes several times during your pregnancy, in your post-birth months and across your time breastfeeding. The only way to handle this is to select a bra that fits your body now and not the size that you used to be or hope to be.

The elastic and support in bras and underwear stretches over time and with wear, so if you are committed to your exercise program or you are a regular gym junkie, don’t hesitate to invest in a comfortable, well-fitted nursing sports bra. Replace it every three to 12 months depending on usage. And remember to ditch underwire bras!

Nursing activewear such as Cadenshae has an amazing range of nursing sports bras, tanks and hoodies that are specifically designed for exercising mums. Wearing well-fitted and functional nursing bras and clothing also means you can easily feed your baby pre/post-workout without contorting yourself in your old gym gear.

Mastitis means no workout today!

If you ever have mastitis you may experience flu-like symptoms such as body aches, breast pain, fevers and/or chills. If you experience these symptoms you will need to skip your workout and visit your GP. You will not be feeling well, and exercise may actually make matters worse.

Blocked ducts and mastitis symptoms are very similar, except mastitis symptoms are more intense and often you may see red streaks on your breast in the affected area. Mastitis is most common during the first few weeks post-birth, but it can occur at any time.

If you are experiencing blocked ducts, you may be able to continue a low-impact workout while wearing loose-fitting clothing. Feeding your baby regularly and wearing non-restrictive clothing/bras will help these clear up. Monitor blocked ducts carefully, as they can easily turn into mastitis.

Optimal nutrition

During pregnancy and lactation, your baby will draw all the essential nutrients needed for their optimal health and Mum will be left to function with whatever is left. You need to nourish your body with everything it needs for the both of you or you will suffer from low energy levels and slow recovery from workouts. 

Now is not the time to restrict calories. Your body will burn approximately 300 to 500 additional calories per day while breastfeeding, so it is little wonder that breastfeeding mums are constantly grazing. Cutting calories could influence your milk supply, so do not focus on rapid weight-loss during the postnatal phase.

To give yourself the energy levels you require to care for a new baby, you need a healthy, balanced diet, so be sure to eat a wide variety of colourful vegetables and fruit and quality protein sources. Continue to take a pre/postnatal women’s multivitamin to help your body function at its best and assist with milk production. 

Carefully check the labels of protein shakes, supplements or meal replacements, as many of these are not recommended during lactation.

Staying well hydrated will also encourage a good milk supply. Whenever you sit down to nurse your baby, ensure you have a full water bottle close by so you can drink and rehydrate your body too. If the weather is hot and you are nursing and exercising, your daily water needs will increase significantly, so you must up your water intake even more than usual.

Seek further support

Everyone’s breastfeeding journey is different and sometimes problems might occur. If you want to continue to nurse as long as you can, be sure to have the right people on your side.

There is a wealth of support in the local community to help you successfully breastfeed. For more information and support, contact the Australian Breastfeeding Association, a lactation consultant, your midwife, community health nurse or GP.

Breastfeeding can be a wonderful bonding experience and you can still achieve your fitness goals with your baby. With a bit of planning, support and knowledge you will find that a nursing baby is no barrier to fitness success. Your baby may even prove to be your secret little weapon and source of inspiration.


1 Daley, A. J., et al. (2012). Maternal exercise and growth in breastfed infants: A meta-analysis of randomized controlled trials. Pediatrics, 130(1): 108-114.
2Carey, G.B. & Quinn, T. J. (2001). Exercise and lactation: Are they compatible? Canadian Journal of Applied Physiology, 26(1): 55-75.
3 Quinn, T. J. & Carey, G. B. (1999). Does exercise intensity or diet influence lactic acid accumulation in breast milk? Medicine and Science in Sports and Exercise, 31(1):105-110.
4 Carey, G. B., Quinn, T. J., & Goodwin, S. E. (1997). Breast milk composition after exercise of different intensities. Journal of Human Lactation, 13(2): 115-120.
5 Lovelady, C. (2011). Balancing exercise and food intake with lactation to promote post-partum weight loss. Proceedings of the Nutrition Society, 70(2): 181-184.
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