The conventional view of adipose tissue was akin to a battery – excess energy (calories) were stored in a manner which could be later used to supply energy needs. This view was prevelent even until fairly recently.

These days, scientists know better.  According to Rexford S. Ahima, an endocrinologist at the University of Pennsylvania, “In the old days, people used to think fat tissue was a passive organ… Now it’s obvious that it makes and secretes more hormones and proteins than probably any other organ. It’s at the center of a very complex system. It coordinates how much we eat, how much energy we burn, how the immune system works, how we reproduce.” (1)

The new view of adipose tissues reinforces a lot of the convential wisdom and observations. People with an overabundance of fat relative to lean body mass have higher incidences of a wide variety of conditions and aliments. Extremely low body fat in women can cause a stoppage of menstrual periods (Amenorrhea) – which maybe able to be treated with synthetic hormone therapy (2).

The new “conventional wisdom” is that adipose tissue is an integral and exceptionally important part of the body’s endocrine system – vital for the maintenance of the delicate body hormonal balances. In fact, Adipocytes also reported to provide a stored source of estrogen in breast tissues with levels of intracellular estrogen changing during the menstralcycle and particularly in menopause, when gonadal contributions to estogen fall off and yet local levels in the breast are not affected on the same scale – meaning local production of estrogen is the key driver of action rather than circulatory levels (4). (Many women who have been through weight fluctuations are keenly aware of the linkage between body fat and hormonal levels – and probably scratching their heads in wonderment that the world of science has only recently caught up to reality!). Adipocytes are are also a major site of fatty acid metabolism, lipogenesis, and production of lipid  mediators that  exert effects on surrounding tissues.

Much more work on this topic is in the works and there are a few theories and even more questions to be answered (including questions on differences between adipose tissue at different locations in the body.