Meet FIL - also known as Feedback Inhibitor of Lactation - a substance found in your breast milk. Research suggests this whey protein, found in breastmilk, contributes to regulating your milk supply. Of course it is not just this simple there are a few other factors but this is one of them.
The absolute basics of it: the more milk you have in your breast, the more FIL you have in your breasts, which tells your body to SLOW milk production.
When you are feeding or expressing regularly from the breast this whey protein does not have time to accumulate in large amounts. With less FIL in the breast your body ramps up production to fill 'em up.
In reverse if you leave your breasts to “fill up” the amount of FIL in the breasts increases and in turn, down regulates the production of your milk. Making milk more slowly, this is a bit of a protective factor - imagine what would happen if your milk production rate was constant! They would burst the first time your baby slept through the night!
How can you make this work in your favour?
If you have a low supply and you are wanting to increase your supply what is the best way? Frequent, effective removal of milk. The more frequently you remove milk from the breast the lower the rate of FIL, and so the faster the rate of your production!
Oversupply can also be controlled by the same principles but in reverse. By draining the breast only as often as your baby feeds and avoiding additional milk removal. The FIL is able to accumulate and decrease the rate of your milk production. Over a period of time your milk production gets the memo to regulate down to what you need. If you keep expressing off the extra milk your body will keep producing it. If your aim is to normalise/decrease your supply then you need to limit what you express and keep it to comfort rather than drain your breast.
End of the day message:
Fuller breasts = Slower milk production
Emptier breasts = Faster milk production
Utilise this to manage your supply in the way you need. If you need further support, book in for a consultation to discuss other strategies you can utilise to get the optimum supply for you and your baby.