Overfeeding a Baby with a Bottle vs. the Breast

Picture this: A hose.

A bottle is a hose that is uncapped. Water turned on? Water comes out. There’s very little that can be done to control it. It comes out fast. Take most bottles and turn them over. The milk streams out of the nipple. with some bottles you have to apply slight compression to the nipple, but not usually.

A breast is like a hose that has one of those sprayers attached. The water’s there. It requires that the water be released. And there are multiple ways in which the water can be released. Baby learns to control the flow by nursing differently for different purposes. Take your shirt/bra off. Lean over. Does milk pour out until your breasts are empty? Chances are.. No. At most you might leak a bit.

The reason why you can overfeed a baby with a bottle very easily but can’t easily overfeed a baby at the breast have two components:

1- Baby-controlled flow.

2- The difference between how “supply” functions within the breast and how “supply” functions with a bottle.

Babies are programmed to suck for a variety of reasons because their instincts evolved alongside breasts and not bottles. Breasts require stimulation to produce milk and to maintain supply.

In the early days when baby’s just learning to nurse, isn’t very efficient, is at risk of starving, etc. mom’s breasts release milk VERY easily and baby needs this. As baby gets more efficient mom’s supply slows down, baby learns to suck harder to get more milk, suck more shallowly to get less milk, and baby learns non-nutritive suckling that provides comfort, communicates with mom’s immune system to get antibodies for pathogens baby’s exposed to, and helps maintain supply where baby needs the supply to be.

Breasts and babies are also in a delicate dance. It’s a conversation. Baby needs to work for food otherwise there will be no food. So baby constantly works to keep supply up to meet baby’s growth requirements and to increase supply during growth spurts. Mom’s body on the other hand has a vested interest in lowering supply. Too much milk means mom’s at risk for mastitis, plugged ducts, etc. It also means that mom’s nutritional reserves are basically leaking out into her bra instead of feeding her baby or nourishing her body. Nature doesn’t like this and works to lower mom’s supply while baby works to increase it. The human breast creates a protein that inhibits lactation. It creates this protein when mom’s breasts have mik in them. This means that if mom goes for a longer period without nursing, her supply will drop. Bottles have no “decrease in supply” and adults are habit driven and tend to fill bottles with the same amount all the time always, or increase it.

Since baby has to work for the food that baby consumes, baby’s sucks are going to be harder and stronger when baby’s hungry or upset. As baby calms down and is no longer hungry baby’s sucks will become more relaxed and turn into non-nutritive comfort sucking.

Again- turn a bottle upside down. Poke at the nipple. Chances are you’re gonna get milk streaming out like there’s no tomorrow. Take baby’s calmer non-nutritive comfort sucking that is biologically engineered into baby and instinct driven and you’re still pouring milk into baby.

Combine that with a caregiver that doesn’t understand a breastfed baby’s hunger cues, that believes in large bottles, or that feeds baby at every given opportunity and suddenly you have a baby that is eating 6oz bottles every 3 hours which essentially is double baby’s needed intake. Many caregivers also feel that baby needs to “finish the bottle” and will continue to offer the bottle to the baby even if the baby is turning away.

It IS possible to over-feed a breastfed baby at the breast. It’s just uncommon and it requires that both mother and baby have something out of the norm. Ie: A baby with reflux and a mother who is taking a medication that increases supply and that has hyperactive letdown. A baby who is in this situation is not going to be asymptomatic though. And this type of situation is pretty rare, whereas a situation where baby’s over-eating from a bottle is more the “norm” than the exception.

Another issue is that bottle feeds tend to be constant across a 24 hour period. Mom’s supply tends to be variable across a 24 hour period. Breastmilk is very easy to digest. Baby will take what baby needs from the milk and poop or pee out the rest. So if baby’s eating 6 oz bottles of pumped milk every 3 hours, baby’s going to poop a ton, gain weight very rapidly, have a stretched out belly, and will be eating 48oz of breastmilk per day that mom has to pump vs. if baby was eating directly from the breast where the average intake for meeting the needs of a breastfed baby is 25oz/24 hours (varying from 19 oz-30 oz.) Drastic over-feeding. Baby doesn’t need it, baby will poop it out, and baby will learn to over-eat and associate “very full” with “done eating” rather than “no longer hungry”. This perpetuates the cycle of drastic over-feeding and often makes mom feel that she “isn’t making enough” because baby learns to prefer the fast flow and easy food of the bottle.

Best practice for mom’s supply and for baby’s health is this: When a bottle feed is necessary,  limit bottle feeds and provide smaller more frequent bottle feeds rather than large feeds. This allows baby’s system to use everything in the milk rather than just flushing it out quickly. It allows mom’s supply to function at more normal levels, and it enforces healthy eating habits in baby.

References: http://www.kellymom.com/bf/pumping/milkcalc.html

  7 comments for “Overfeeding a Baby with a Bottle vs. the Breast

  1. laura
    May 6, 2012 at 3:20 pm

    So I work full time and my guy is in daycare M-F from say 8:30-6:30 on a bad day and 9:00-5:00 on a good day. He will be 8 months in 2 days. He is doing 2 “meals” at daycare and more often no meals ay home. He is taking 3 bottles: 3-5oz, 6-6.5oz, and 5oz. How do I wean him to drink less at daycare without 1)the workers think Im starving him and 2)him think Im starving him?
    He is a big breast fed baby. He was at 19lbs on breastmilk alone at 6 most. He was 20 pounds 10 oz on Friday. He nurses well at home- at 8pm, 12am, 5am, and 6am. I would just love to not have to try to pump 18oz at work to have enough for bottles and cereal. Any advice would be greatly appreciated.
    Love your blog :)

    • sarah
      May 6, 2012 at 3:47 pm


      I would start off by nursing him just before dropping him off at daycare, and then try either decreasing each milk feed by one ounce per feed per week, or make the bottles 3oz each and request that only one bottle be given at a time. Some babies (especially more active babies) will be distracted enough at daycare that they won’t look for another bottle and will space out their feeds more themselves and then nurse more at home. The goal is 1-1.25oz per hour of separation: (The “one ounce per hour rule“)

      Talk to the daycare owner or manager about “reverse cycling” and see if you can get them on board. Solicit their feedback about how he acts during the day and wean back the daycare feeds slowly. I definitely wouldn’t do anything sudden. Since your LO is used to large feeds at daycare it may be a bit difficult to wean off of. But he’s definitely getting a LOT of milk from the bottle on top of the solid meals that he is getting and is likely nursing less at home as a result.

      On the plus side, since you’re 8 months in and your milk supply isn’t suffering you’re likely not going to be one of the ones that has difficulty keeping up with the supply even if it is annoying having to pump 18oz at work.

  2. June 13, 2012 at 4:53 am

    Thank you!! Oh my gosh that is great to read. I will be heading back to work in a little over 8 weeks (sniff) and my son will be 5 1/2 months. He is already familiar with bottles (due to a 6 week stay in the NICU after he came 9 weeks early) and I started pumping the morning after he was born so I still have a decent supply frozen but have been trying to figure out the bottle thing once I go back to work. My schedule isn’t set and varies a lot and he will only be getting bottles when I am working. This gives me good info on how to start the process out right!

  3. January 6, 2013 at 4:02 pm

    My son was 9 weeks early and spent 9 1/2 weeks in the NICU, and they taught us how to bottle-feed in a healthier way that does not promote overfeeding. Lay the baby on his side, as he would be while nursing. Hold the bottle horizontal so he has to suck to get milk out. Use a slow-flow nipple. Run the nipple across baby’s mouth so that he opens his mouth for it rather than forcing it in. Don’t force a baby to finish a bottle, and if he’s still acting hungry when he does, give him more milk. Feed on cue rather than on a schedule.

    Just wanted to point out that all bottle feeding is not the same. It’s never going to be exactly like nursing, but there’s definitely a better way to do it than what you alluded to (inverting the bottle, etc.).

    • sarah
      January 6, 2013 at 5:55 pm

      Ix There are definitely healthier ways to bottle feed. Paced feeds, smaller bottles, horizontal bottles with slower flow, etc. All can make for a healthier bottle feeding technique. Not all bottle feeding is overfeeding, bottles just make it much easier to accidentally overfeed.

      Many people believe that if a baby is sucking at a bottle they need more food, so I hear about one week old babies consuming six ounce bottles with their daycare and then throwing up.

      Understanding how overfeeding can happen with a bottle makes it easier to understand why certain things such as a horizontal bottle, slow flow nipple, etc. Are good ideas.

  4. Eric
    June 2, 2014 at 9:32 am

    Enjoyed the read. Dispdnt quite understand the following sentence.


    Does it mean your baby will not feel satiated when he’s full after feeding? Thanks for any comments.

    • sarah
      June 2, 2014 at 10:46 am


      When we are hungry there are two ways to approach it. We eat until we are no longer hungry, or we eat until our belly feels full. The two aren’t the same. When we eat until we are no longer hungry we graze until the feeling of hunger goes away. When we eat until we are full we gorge until our belly can’t hold any more. When we eat less and simply eat until we are done feeling hungry, we digest what we have eaten and we use it more effectively. When we gorge on food a lot of it ends up wasted.

      When a baby eats from the breast it’s harder to get the milk out, so they’re less likely to passively eat large amounts of food until their belly can’t hold any more. They have to work for the food, so they tend to eat until they are no longer hungry rather than eating until they are very full. This means that they eat more often, use more of what they eat, and follow healthier eating patterns.

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