In infants, brown adipose tissue deposits include: interscapular, supraclavicular, suprarenal, pericardial, para-aortic and around the pancreas, kidney and trachea.

[16][17] Brown fat in humans in the scientific and popular literature refers to two cell populations defined by both anatomical location and cellular morphology.

Both share the presence of small lipid droplets and numerous iron-rich mitochondria, giving the brown appearance.

In neonates (newborn infants), brown fat makes up about 5% of the body mass and is located on the back, along the upper half of the spine and toward the shoulders.

[25][26][27][28] One study of APOE knock out mice showed cold exposure could promote atherosclerotic plaque growth and instability.

Furthermore, several newer studies have documented the substantial benefits of cold exposure in multiple species including humans, for example researchers concluded that "activation of brown adipose tissue is a powerful therapeutic avenue to ameliorate hyperlipidaemia and protect from atherosclerosis"[30] and that brown fat activation reduces plasma triglyceride and cholesterol levels and attenuates diet-induced atherosclerosis development.

Pharmacological approaches using β3-adrenoceptor agonists have been shown to enhance glucose metabolic activity of brown adipose tissue in rodents.

[32][33][34] Additionally research has shown: The interscapular brown adipose tissue is commonly and inappropriately referred to as the hibernating gland.

[57] Whilst believed by many to be a type of gland, it is actually a collection of adipose tissues lying between the scapulae of rodentine mammals.

[58] Composed of brown adipose tissue and divided into two lobes, it resembles a primitive gland, regulating the output of a variety of hormones.

[62][63][64][65][66] However, brown fat is unlikely to play a role in body temperature regulation of many large-bodied mammals as the UCP1 gene, encoding for the key thermogenic protein of the tissue, has been inactivated in several lineages (e.g. horses, elephants, sea cows, whales and hyraxes).

A reduced surface area to volume ratio among large-bodied species decreases heat loss in the cold, diminishing thermogenic demands required to defend body temperatures.

UCP1 loss in other species (e.g. pangolins, armadillos, sloths and anteaters) may be linked to selection pressures favouring low metabolic rates.