Does Working Out While Breastfeeding Affect Breast Milk Supply?

Last Updated on 2 years by Eva

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Physical activity is an important part of your postpartum weight loss journey. Not only it provides the additional fat burn, but it also helps you to recover a lot sooner, improves your health and energizes your body. Studies indicate that moderate exercise is safe for your baby and does not have any side effects on it’s growing. After my first delivery, I didn’t exercise until 6 months postpartum because I was told that my breastmilk supply could drop. It is natural for a first-time mom to have concerns and doubts about exercise while breastfeeding. You want to lose weight but at the same time, you don’t want to do anything to endanger the only food source for your baby. On the other side though, as a nursing mother, you need to care for your well-being to be able to satisfy that exceptional demand breastfeeding places on your body. Staying fit is one of the ways to look after yourself. So will working out while breastfeeding really affect your milk supply or your baby in any way? Will it change breastmilk´s taste or quality? Let’s find out.

Don’t worry about the taste or quality

The first question I’ve asked my personal trainer when I started my postpartum training was if the exercise will make my milk taste differently. Some of you may have heard that working out while breastfeeding can make breastmilk “sour” as the lactic acid level increases after exercise. This is actually true providing that you exercise very intensively. Lactic acid is the body´s natural substance that is not harmful to the baby in any way and disappears from breast milk quite quickly (in approx. 90 minutes). Studies have not shown a noticeable increase of lactic acid after moderate physical activity. So as long as you stick with some low-impact workouts ( up to 80% of maximal heart rate range), you will be fine. If your baby is fussy when nursing after exercising, it may be due to your sweaty skin, not the milk itself. I have always breastfed my son 15 minutes before I started my training and then usually about an hour after I finished. When your baby wants to eat right away after training, you might want to wash off your boobs a bit and express a little milk (3-5 ml from each breast) before nursing. I have to admit that sometimes when I was in hurry or my son would cry a lot, I didn’t fuss around with expressing milk or cleaning the nipple. But none of my sons seemed to be bothered by that.

Studies also show that moderate exercise does not have any effect on breastmilk nutrient composition – it provides the same quality of nutrients to your baby whether you exercise or not.

It won’t decrease your milk supply

There are series of researches that deal with how physical activity affects breastmilk supply. The results show that there is no difference between the mother´s milk supply whether she leads a sedentary lifestyle or is an extremely active athlete (e.g. marathoners or triathletes). Moreover, they discovered that women who exercised daily experienced outstanding benefits compared to inactive women:

  • their milk supply increased
  • their breastmilk had higher energy content
  • they had more energy and higher aerobic capacity

There is no reason why you should give up exercising just because you breastfeed. As long as you eat healthily and keep yourself hydrated, the workout should not have any effect on your milk supply. Hydration is key when exercising, so make sure that you stay hydrated before, throughout and also after your training. Dehydration can lead to producing less milk! Keep a water bottle with you at all times so you won’t forget to drink up.

Plan your workout time

This is actually the tricky part because once you turn into a mother, the timing becomes a hard task. You think you are all set up and ready to go and then the baby burps all over you, himself or the car seat. Sometimes, it is just completely out of your hands.

I’ve been always a “planning freak”, it just made me feel more secure when I had my day or week planned ahead. With kids, it obviously gets harder, but it is not impossible 🙂 When I started to work out, I had to plan my training around my baby´s feeding and sleeping schedule. When my son was 2-3 months old, he just wanted to eat all the time. So I used to arrive at the gym 15 minutes earlier and breastfed him. After an hour-long workout, I washed, expressed a little milk and fed him again before getting into the car. Now, being 4 months, his eating intervals are longer, so I always feed him at home before leaving to the gym and then again when we get back home. I try to plan my workouts in the morning from 9-11 pm, as this is the time when he usually sleeps. Most of the time, he sleeps in the stroller through the entire workout. And, if he doesn’t, my trainer carries him around the gym.

If you don’t feel comfortable with all this hustle, try to work out at home the first months. As your baby gets older his/hers feeding and sleeping schedules will get more predictable. You will find it easier to plan a workout outside your home.

What comes in handy

There are many things I wish I had known when I first tried to balance breastfeeding, the baby´s routine and workout schedule. Here are some tips so you’ll be better prepared than I was:

  1. Invest in a good supportive sports bra. Before breastfeeding, I had small breasts so I never really cared about supportive bra when working out (apart from those padded sports bras for maximum volume :D) I was taken by surprise when, during my first real training, my boobs hurt with every move. So my advice to you – get yourself a good, high-impact bra beforehand – you won’t regret it! Ideally, with easy-access openings for nursing. Don’t forget to take it off as soon as you finish your workout to avoid mastitis or clogged ducts.
  2. Work out with empty breasts. Simply because exercising is much more comfortable this way. Breastfeed or pump before you start.
  3. Carry along some nursing pads. Especially during the first months postpartum, the boobs leak unexpectedly. Mine leak a LOT so nursing pads always come handy. I use washable pads made from bamboo, as they are extremely soft and do not stick to the nipple. Also, bamboo fiber holds the body temperature much better than other clothes, so the wet nursing pad does not feel uncomfortable when touching your skin.
  4. Pack a snack. Before kids, I used to eat a protein bar after my training, but since these kinds of supplements are not recommended while breastfeeding, I always pack some fruit, flapjack or a smoothie. When my blood sugar level drops, I get dizzy. I try to prevent this state as much as I can when I have to run around with the baby.

The value of self-care

Every mama needs a “me” time and exercising is a great way of spending it. I know the first months postpartum can be overwhelming and it is hard for you to actually find a time for a decent shower. But try to squeeze in some physical activity if you can – it will work wonders for you, both physically and mentally. You NEED your “me” time to be able to care for your family. Because if mama ain’t happy, ain’t nobody happy.


Do you have a different experience with exercising vs. breastfeeding? I would be happy if you let me know it the comments.




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