Compared to most other, non-aquatic animals, we give birth to infants with relatively amounts of body fat. This has been hypothesized to explain why our infants can sustain a weight loss of 8-10% after birth while receiving immune factor rich colostrum. Infant body fat frequently increases across the first few months of life, and it is generally thought that this is in anticipation of nutritional stresses that may be associated with weaning and independent motor development (crawling, walking). However, baby fat is not all the same – babies actually have multiple different types of fat (also called adipose tissue). When it comes to BAT, BeAT, and babies, we actually know very little about the production and maintenance of BAT and BeAT (this is actually true for all ages). What can explain the differences seen in rates of BAT and BeAT decline in different infants based on the handful of studies? The answer may be BREAST MILK.