Let me guess, you are one of those moms who is active during and before pregnancy and you are wondering the effects of exercise on breastmilk? 

Well, if you are that mom and

1. need to exercise for your sanity,

2. like to exercise because it makes you feel fabulous, or

3. are looking for motivation to put on those running shoes, you should know this:

Please exercise away! Here are the deets:

Is exercise recommended?

Yes! the US Centers for Disease Control recommends that pregnant and postpartum women engage in at least 150 minutes of moderate-intensity aerobic exercise spread throughout each week. Exercise after having a baby is associated with lower rates of postpartum depression and baby blues. Getting your move-on can even help you feel more closely bonded with your baby. And prioritizing exercise, no matter what it is (walking, running, CrossFit, Beachbody, lifting loads of laundry), can help you make sure you get time for yourself! 

Does exercise decrease your milk supply?

No! In a study in women, who kept a consistent diet and fluid intake, it was shown that there was no difference in the volume of breastmilk expressed after exercise as compared to after resting. The key here is hydration! But if any of you know how extremely thirsty you get when breastfeeding, never-mind when participating in exercise, you should have no problem drinking enough water. If this is a worry for you, treat yourself to a nice water bottle and keep a spot for it in your breastfeeding space so that it is always by your side when you plop down for a feed.

Does exercise decrease the nutrition in my breastmilk?

No! Again, in recent research, it is shown that breast milk samples after rest as compared to after exercise showed NO differences in protein, fat, lactose, or calories.

Is there anything that changes in your breastmilk with exercise?

Yes, but not to worry. High intensity exercise (i.e. maintaining a heart rate between 70 and 90 percent of the maximum heart rate) has been shown to increase the amount of lactic acid in breastmilk. Lactic acid affects the taste of breastmilk. However, few moms say that this is related to poorer feeds after intensive exercise due to higher lactic acid (sometimes babies can be distracted by the salty flavor of the sweat on your breast). If you are seeing that feeds are not going as well, you can try to express ½ -1 ounce of breastmilk before nursing baby or just postponing feed for a half hour to let the levels of lactic acid decrease. You can also decrease the intensity of your workout.

So, yes, throw on those old sneakers momma (or definitely treat yourself to some new ones)! We know from extensive research that there is likely NO impact on your baby’s breastfeeding or weight gain as a result of you exercising.

Have more questions about breastfeeding baby? Check out NurtureTalk or see our informational post on 6 Ways to Make Life Easier When Feeding a Newborn.


“Emily was a huge help to me with the early days and weeks of breastfeeding. I’ve gotten her help with issues that have come up later as well. With her background as both an IBCLC and a dietitian she has the knowledge to help with the many stages of newborn to infant to toddler feeding and is a great problem solver. Texting with Emily as questions came up had a huge positive impact on my breastfeeding journey and the health of my children.”

Margo, MA

Emily Sylvester is the Founder or NurtureTalk and has worked as a pediatric Registered Dietitian and International Board Certified Lactation Consultant (IBCLC) for over 7 years. She has worked closely with breastfeeding families, NICU graduates, babies who are substance exposed, and children who need help to grow and thrive. Emily specializes in infant and toddler feeding and provides nutrition care in homes, schools, community groups, and outpatient clinics. Emily is the president of the Massachusetts Breastfeeding Coalition and helped to establish a Baby Café in Boston, MA. Emily obtained her master’s degree in nutrition from the University of Rhode Island and graduated from the National Institutes of Health Dietetic Internship. Emily is the proud mother of 2 and 4 year old girls, 7 month old baby boy, and was recognized as the 2018 Recognized Young Dietitian of the Year through the Academy of Nutrition and Dietetics. Emily founded NurtureTalk to help fill the need for more affordable, accessible, timely, and tailored infant feeding information; this information aims to support families in their feeding journey, in an unbiased manner, from pre-birth through 1st birthdays.