Feb 10, 2026 Lactation Practice Notes
Evolve Lactation Pros
Let’s Talk About Adipose Tissue
In my reading about breast health, adipose tissue featured prominently.
Let’s go deeper than we usually do when we learn about it in relation to lactation.
When we are born, we have both White Adipose Tissue (WAT) and Brown Adipose Tissue (BAT).
Each has its own structure and function.
BAT is the thermogenesis specialist. It produces heat. This is critical for infants because it is harder to keep a smaller body warm. As the body ages, most of the BAT involutes as it is no longer needed. Adults do retain a small amount of BAT, located mostly in the supraclavicular region near the neck. This is why it is theorized that BAT is retained in adults in order to help keep blood flowing to the brain including during times of cold stress.
*Lactation Note: Late Preterm and Preterm infants are born with less BAT since they have had less time to accumulate it. This makes them more susceptible to cold stress; it is why continuous skin to skin is recommended for these babies as it prevents insensible heat loss.
WAT is energy storage tissue that also functions as an endocrine organ, secreting hormones like leptin and adiponectin.
But the magical part about WAT is that during pregnancy, it transforms into Pink Adipose Tissue (PAT) - these are the milk-secreting endothelial cells we are always talking about when we think about the fundamentals of milk production!
A tissue that we already have literally changes itself into a tissue with a different function in order to make milk to protect our offspring. And then when lactation ends, it transforms BACK into WAT to store energy for the body again.
The human body never ceases to amaze.
*Lactation Note: We should keep in mind that this transformation happens during early pregnancy, resulting in the tissue that kicks off milk production by around 20 weeks gestation. (Remember that the high level of circulating progesterone during pregnancy suppresses milk production until shortly after birth.)
Once the placenta is expelled after birth, the body shifts into full milk production, and within approximately 48-72 hours, we expect to see copious milk production.
All of this happens regardless of whether there is breastfeeding or milk expression. Once copious milk production has begun, then the body switches from autocrine to endocrine control of lactation.
This is all crucial knowledge for us to bring to the conversation about lifetime breast health because people need to know that once the WAT has transformed into PAT (and other changes have occurred in the breast tissue to make it capable of making milk), there will also follow a return to the pre-pregnancy state in the breast. Basically, it has to go back to what it was before, regardless of whether the individual breastfeeds or expresses milk for any length of time.
Further, we have learned from the research that when this transformation is forced to occur suddenly and before 180 days postpartum, it happens in a way that leaves the breast tissue more vulnerable to tumor growth.
That is what a lack of breastfeeding does to the breast tissue. This is why breastfeeding is not a “lifestyle choice,” but a critical health behavior.
It is what makes our work vital. Thanks for doing the work, day in and day out.
