Many breastfeeding individuals have concerns about maintaining an adequate milk supply when returning to exercise, especially those exercising at high intensity and high volume pre-pregnancy and would like to return to that training level. Given the energy demands and logistics of breastfeeding and exercise, there are nutrition considerations to help the breastfeeding parent be successful and stay healthy while returning to the level of exercise that they desire.
The good news is that it is well established that exercise does not impact the quality or volume of milk production.(7) In fact, even high intensity exercise (100% VO2max) does not compromise the milk quality, despite the myth that the lactic acid build up in milk will negatively alter the taste and deter the baby. Lactic acid taste threshold in water is 1.5 mM, while the lactic acid concentration of breastmilk 30-60 min post exercise is 0.94 mM, so it’s unlikely the baby will even taste it.(2) Additionally, this concentration declined at the 90 minute mark.
Breastfeeding requires an additional 500 calories per day, which is about the amount of calories in a meal, or a couple of snacks.(3) Keep in mind that with returning to sport/exercise, additional calories may be needed, in addition to this breastfeeding caloric requirement!
It is not recommended to lose more than 4.5 pounds of weight per month in the postpartum period. Rapid weight loss may indicate under-fueling, which may affect not only the milk supply, but also the overall health of the individual. Protein needs while lactating may increase to the equivalent of an athlete in a heavy training period! One small study in eleven breastfeeding women suggests protein needs may be 1.7-1.9 g/kg protein per day.(4)
While any new parent is fatigued by the demands of a baby and sleep deprivation, still take note of energy levels and stay on a regular meal and snack schedule. While some people may fuel adequately and prefer 3 large meals daily, others may require 3 large meals, and 2-3 snacks or mini meals for those with high energy needs. Aim to include all food groups at each meal, and at least 2 food groups (including protein) at each snack to get balanced nutrition and meet the energy demands of breastfeeding, parenting, and being active.
A prenatal multivitamin is still recommended as certain vitamin/mineral needs remain elevated during lactation.(3) Calcium in particular is very important while breastfeeding. Breastfeeding can cause loss of bone mineral density that exceeds the loss of what occurs post-menopause! The good news is that bone loss during breastfeeding is usually recovered within a few months after stopping breastfeeding, and both resistance training and aerobic exercise can prevent as much bone loss while breastfeeding.(6) However, ensuring you are meeting 1000 mg of calcium daily can play a protective role. Sources of calcium are dairy, fortified dairy alternatives, dark green vegetables like collards and broccoli, and canned fish with bones.
Fluid & Electrolyte Needs
There is no standardized recommendation for fluid intake for a lactating person. Certainly, fluid needs are higher than during the non-lactation period. General recommendations are roughly 3 L per day in addition to replacing the losses through exercise.(3) Going above and beyond hydration needs will not increase the milk supply.
For reference of exercise fluid losses, the average sweat rate is about 0.5-2 L/hour, and it’s best practice to re-hydrate with 24 ounces of fluid for every 1 pound lost during exercise. Typically, it’s recommended to monitor urine color for hydration status, but a prenatal vitamin may alter the urine color to a more neon yellow. Stool (yes, your poop!) consistency is another way to monitor your fluid status: hard/dry stools may indicate dehydration.
Two athlete moms interviewed for this article both mentioned drinking electrolyte/sports beverages as helpful for meeting hydration needs, even on days without exercise.
Tips from Working Mom Athletes
- Both observational research in elite athletes returning to sport and anecdotal evidence in speaking with athlete-moms, pumping milk is a common recommendation in getting back into sport and exercise as it offers more flexibility with feeding, especially if there is a co-parent available to help with the feeding.(1,6)
- If pumping while training, it might be helpful to stash a portable pump in the gym bag, because exercising can be extremely uncomfortable to exercise with full breasts. Cleaning the breasts after a workout before nursing/pumping can also help with mastitis prevention.
- Heidi, ultra-endurance runner and sports dietitian who competed in 50ks while breastfeeding for both her children shared this: “The biggest factor for maintaining supply for me was hydration, as well as getting in enough calories. Usually I have no problem getting in enough but with both my daughters I pumped a lot too, so I was producing a lot of milk but also burning a lot of calories. With both of my daughters, my supply did start to dip around 6 months postpartum, and I was determined to make it a year exclusively breastfeeding. So, I pulled back on my training a bit and increased my intake, specifically through oatmeal, sports drinks, and nuts/nut butters to get my supply back on track.”
- Kelly, active mom of two and sports dietitian, is another supporter of eating oatmeal while lactating: “While there isn't quite enough research to support benefits of galactagogues, I do believe in the limited evidence that suggests the beta glucan in oats may indirectly support production. When I consistently choose oats for breakfast, I do feel my supply is greater.” Kelly also mentioned sports drinks were helpful in meeting her fluid and electrolyte needs.
While getting back to exercise and training is possible for some while breastfeeding, parenting, working, etc., it’s important to recognize that you are a human first and to honor what you feel your body really and truly needs. For some, backing off on exercise may help with milk supply, overall stress, and your health. For others, that may be discontinuing breastfeeding and moving toward using formula. Give yourself grace and recognize that exercise, training, and sports will be there for you if or when you truly ready.
- Giles, Audrey R., et al. “Elite Distance Runners and Breastfeeding: A Qualitative Study.” Journal of Human Lactation 32.4 (2016): 627-632.
- Kominiarek, Michelle A, and Priya Rajan. “Nutrition Recommendations in Pregnancy and Lactation.” The Medical clinics of North America vol. 100,6 (2016): 1199-1215. doi:10.1016/j.mcna.2016.06.004
- Rasmussen, Betina et al. “Protein Requirements of Healthy Lactating Women Are Higher Than the Current Recommendations.” Current Developments in Nutrition vol. 4,Suppl 2 653. 29 May. 2020, doi:10.1093/cdn/nzaa049_046
- Sundgot-Borgen, J., Sundgot-Borgen, C., Myklebust, G., Sølvberg, N., & Torstveit, M. K. (2019). Elite athletes get pregnant, have healthy babies and return to sport early postpartum. BMJ Open Sport & Exercise Medicine, 5(1). https://doi.org/10.1136/bmjsem-2019-000652
- Lee, L. L., Huang, S. F., Lai, P. C., & Huang, Y. T. (2020). Effect of exercise on slowing breastfeeding‐induced bone loss: A meta‐analysis and trial sequential analysis. Journal of Obstetrics and Gynaecology Research, 46(9), 1790–1800. https://doi.org/10.1111/jog.14346
- Tenforde, A. S., Toth, K. E., Langen, E., Fredericson, M., & Sainani, K. L. (2014). Running habits of competitive runners during pregnancy and breastfeeding. Sports Health: A Multidisciplinary Approach, 7(2), 172–176. https://doi.org/10.1177/1941738114549542
- 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. https://doi.org/10.1017/s002966511100005x