Brown Fat Activation (IMAGE) Rutgers University Caption People have a few grams of brown fat that is activated when the body is cold. Brown fat uses sugar, fat and amino acids from the blood to generate heat. Left: Brown fat is not activated. Right: Cold conditions activate the brown fat as shown by the orange color on both shoulders and the neck. Credit Image: Labros Sidossis/Rutgers University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.