Breastfeeding Basics: The Principle of Milk Supply and Milk Demand

Boobs are wonderfully designed to produce incredible milk to nourish our young. It is helpful for all breastfeeding mothers to understand how their boobs know how much milk to make to provide for their baby. 

How much milk your boobs make, depends on how much is demanded of them by your baby. It’s all about the milk SUPPLY meeting the baby’s DEMAND. If a baby feeds often, and moves milk from the breast effectively, then boobs will keep MAKING MILK in response to your BABY.

breastfeeding info

So how does this happen? Lets meet Prolactin and Oxytocin. Prolactin; now she’s a clever hormone who stimulates the milk glands in the breast into action, and Oxytocin’s job is to allow milk to be released from the boobs. [Helpful side note here, Oxytocin is also a feel good hormone!]

breastfeeding supply demand

So that’s HOW my boobs make milk you say, but how MUCH will they make? is often the question. Well there is a big difference from mother to mother as each mother meets the needs of their child, so it’s best not to compare yourself in millilitres to the next mum. But in terms of your milk? Say hello to FIL, or Feedback Inhibitor of Lactation. FIL lives in breastmilk and SLOWS milk production down. So if you have a LOT of milk in your breast, there will be a lot of FIL around, which will SLOW down the milk making.
supply demand breastfeeding

The opposite of this is also true, and this is what’s IMPORTANT to remember when thinking about making milk for your baby. If there is NOT MUCH milk in the boob, then milk making will SPEED up. Of course this will only happen if baby keeps DEMANDING milk through suckling at the breast. Your boob will make as MUCH milk as your baby NEEDS if baby is given OPPORTUNITIES to suckle at the breast and stimulate milk making.

breastfeeding supply demand

Here’s a helpful ILLUSTRATION

Imagine 2 glass jugs (see what I did there?) – one jug is ¼ full, the other jug is ¾ full; but both jugs need to be full in 5 seconds. In order to both be full in 5 seconds, I need to pour water QUICKLY into the empty jug, and SLOWLY into the nearly full jug. Boobs are kinds of the same. An empty boob will make milk faster than a full boob.


  •  Baby must suckle OFTEN to stimulate the breast to MAKE milk – this will be during the day and over night and that is NORMAL and HELPFUL for making milk
  • respond to the demands of YOUR baby - every baby is DIFFERENT, routines and feeding schedules are IRRELEVANT to making enough milk for YOUR baby
  • empty breasts MAKE MILK FASTER
  •  full breasts MAKE MILK SLOWER

supply challenges breastfeeding

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