Breastfeeding A to Z

Weight Loss, Diet & Exercise While Breastfeeding

Weight Loss

Within the first week after your baby is born you will lose roughly 7-10 pounds (3.2-4.5 kg).  In the next three weeks, you will lose the extra fluid (blood volume etc.) you have needed during your pregnancy.  After the three week mark, you are left with some additional fat stores reserved for breastfeeding.  These fat stores, whether you want them or not, are your body’s way of insuring you have enough calories to maintain your milk supply.

You may be wondering if you can start losing some weight.  It is usually not a problem to maintain your milk supply and lose around 1 pound (0.5 kg) per week. (1)  The rate of 1 pound (0.5 kg) per week does not seem to change the quality or the quantity of milk you produce.  If you start to lose more than 2 pounds (approx. 1 kg) per week after 3 weeks postpartum you can effect your milk supply.  It is recommended you don’t go below 1500 calories per day (2)  Gradual weight loss is best for you and your baby.


You do not have to follow a special diet when you are breastfeeding.  Whatever good habits you were trying to follow in pregnancy will still work well for breastfeeding.  A good rule of thumb is a moderate amount of a variety of foods. Think about eating in color.  Different colors of foods provide different nutrients to your diet.  The more “colors” of foods you take in, the greater the variety of nutrients.

Check with your healthcare provider about continuing to take any supplements you are taking during your pregnancy.  Usually, continuing your prenatal vitamin is helpful.  You don’t always have to continue taking extra iron.  Check with your healthcare provider to be sure.  Also, you may have heard that breastfeeding can decrease your bone density.  There is a slight bone loss during lactation, but the bone density is restored after weaning. (2)  It is important to try to consume 4-5 servings of dairy every day or get the equivalent of 1300 mg of calcium per day in supplements. (3)

Often mothers are concerned if something they eat will affect their baby when they are breastfeeding.  There is usually nothing you need to avoid while you are breastfeeding your baby.  If something causes you “gas”, it may do the same for your baby.  Babies often grunt, groan and make faces when they are attempting to have a bowel movement.  This is because their intestinal tract is squeezing (set in motion by their sucking) and this squeezing pushes their stool and any air through there system.  They are not always thrilled when this happens.

The majority of baby’s have no issues with what their mom is eating.  Remember they have had tastes of your diet throughout your pregnancy from swallowing the amniotic fluid. (4) Over the years of counseling mothers and babies, it hasn’t been a very frequent issue that what mother’s ate bothered their babies via their breastmilk.  If this did happen it tended to in families that had a known history of allergies.

If you think a particular food/beverage is causing a problem for your baby, try this simple test.  Keep a record of what you eat/drink, the amount and when you consumed it.  It usually takes 3-6 hours after you have eaten, before it is present in your breastmilk.  If it was a beverage alone, without food, it can be in your system faster in approximately 1-2 hours.  So, if after a feeding your baby seems fussier or more irritable than usual, think back, what did you have to eat 3-6 hours ago.  For beverages alone with no food, 1-2 hours. If you can pinpoint something that you have had that is different or maybe you have had a larger amount of some food/beverage item, try that item again.  Do it early in the day, so that the 3-6 hours after you’ve eaten it is still in the daytime hours–at least you can hope you won’t be dealing with this in the middle of the night.  Try not to take something out of your diet that you enjoy or is good for you based on “one” incident of your baby being upset, fussy or otherwise unhappy.  Your baby can be fussy or more irritable for lots of reasons, not just food what you are eating and drinking.

If you have discovered something that, at least twice, has caused your baby to be more irritable or fussy. Then you can consider taking it out of your diet for 2-3 days and see if the fussiness improves.  If it does, then try taking the food out of your diet for a week or more.  If you see no change then it was probably not the food item and you can continue to enjoy that food or drink. If there is something you are going to take out of your diet on a long-term basis, check to see that you are getting the nutrients it supplies from another source. (Example: take out dairy–replace calcium and protein)  Check with your healthcare provider and/or a registered dietitian for help with this.

If you have a family history of allergies, potentially any food can cause a problem, but most frequently it tends to be dairy products.  Much less frequently, wheat, eggs and corn in mom’s diet can be the culprits for breastfeeding.  Breastmilk has been shown to protect against allergies in infants, especially when mom can avoid the offending food in her diet. (2)  Get the help of a registered dietitian to make sure you are eliminating all the sources of the offending food/beverage from your diet.  For example, eliminating dairy from your diet requires much more than just not drinking milk.  Be sure to seek the advice of your healthcare provider if you suspect an allergy.


Exercising while breastfeeding is safe in moderation; it’s usually more about finding the time to exercise. (2)(5)

If you exercise more than 1 hour per day, watch your weight.  Often if you are doing this much exercise your appetite will increase and you will need the additional calories to keep your weight loss from becoming greater than 1 pound (0.5 kg) per week.  After the three week mark, when you are no longer equalizing fluid and blood volume from delivery, rapid weight loss can decrease milk supply.

If you are having issues with your mood, or have struggled with depression, exercise can be as effective as medication in improving your mental health. (5)

An older study that said babies refused the breast due to high levels of lactic acid after strenuous exercise, has not been found to be the case in more recent studies. (5)  The work of daily living in the past would have been considered strenuous exercise and our ancestors managed to breastfeed their little ones.


  1. Mohrbacher, N, Stock, J, La Leche League International The Breastfeeding Answer Book, 3rd revised edition, Schaumburg, IL, La Leche League International, Jan 2003, pp 446-47.
  2. Lawrence, RA, Lawrence, RM, Breastfeeding: A Guide for the Medical Professional, 7th edition, Maryland Heights, MO, Elsevier Mosby, 2011, pp 187-88, 311, 582.
  3. Kleinman, RE, Greer, FR, Pediatric Nutrition, 7th edition, Elk Grove Village, IL, American Academy of Pediatrics, 2014, p 1357.
  4. Mennella, JA, Jagnow, CP, Beauchamp, GK, Prenatal and postnatal flavor learning by human infants, Pediatrics, 2001, Jun;107(6):E88.  Available at  Accessed Sept 17, 2015.
  5. Mannel, R, Marten, PJ, Walker, M, Core Curriculum for Lactation Consultant Practice, 3rd edition, Burlington MA, Jones & Bartlett Learning, 2013, pp 103, 325.