Brown adipose tissue (aka brown fat) is one of two types of mammalian fat (the other is white fat).  The primary function of brown fat is to generate body heat-  it’s especially important in hibernating animals and newborns that don’t shiver.  (I’m sure it’s even more helpful for hibernating newborn babies…)  Compared to white fat, brown fat has a higher density of mitochondria, which contain iron and make it brown.  Brown fat takes calories from white fat and burns it to generate heat, which could be a new weight loss strategy.  Babies have more brown fat than adults, however.  So, I suppose it would be a great weight loss strategy for fat babies.  Just put them in cold water and they will look great in no time.

NOTE: DO NOT LEAVE YOUR BABY IN COLD WATER

Or you could put the babies on the “baby food diet” as was previously discussed

http://smartestyear.com/post/794887298/baby-food-diet-7-10-10