Baby, coloured thermogram. The colours reveal different temperatures, from white (warmest) through red, yellow, green, blue and purple to black (coolest). The baby's back is very warm due to the presence of large amounts of brown fat. This is a specialised adipose (fat) tissue found in babies that generates large amounts of heat, helping to prevent hypothermia. It is concentrated on the back and shoulders. As the baby grows, much of the brown fat is converted into white fat, which is the primary energy storage tissue in adults.