Sanford-Burnham’s Dr. Sheila Collins recently returned from Stockholm, where she attended a meeting on brown fat (also called brown adipose tissue) and obesity, held in conjunction with the XI International Congress on Obesity. Brown fat, which helps generate heat, was historically thought to be limited to small mammals such as rodents, newborns of larger mammals (including humans), and hibernators – in order for them to stay warm. Scientists used to think that brown fat disappeared after infancy, but recent advances in imaging technology led to a rediscovery of brown fat in adult humans. This meeting brought together scientists studying the basic biology of brown fat tissue and its possible role in adults in order to figure out how all this information can be applied to fight obesity.
Brown fat is brown because it’s full of blood vessels and mitochondria, the part of a cell that generates energy (recall in school we learned that mitochondria are the “powerhouse” of the cell). As in our typical “white fat,” brown fat cells store energy. But brown fat is different because it also has a special molecule called the uncoupling protein, which is like a ‘leak’ in the energy-generating system. With this leak, brown fat cells have to burn more fuel to produce the same amount of energy that other types of fat are able to generate. The net effect is to produce heat.
“It’s like trying to keep the tub filled to a certain level while the drain is open,” Dr. Collins explained. “You have to pour in a lot more water.”
Keeping the brown fat “tub” full means burning more calories. Dr. Collins and other scientists hope that the more we know about brown fat, the more we might learn about how to activate it to help us burn extra calories and lose weight – or prevent weight gain. At the meeting in Stockholm, Dr. Collins talked about her research on how adrenaline activates brown fat and how that mechanism is regulated.
“Most of the people who work in this field were at the meeting, so it was a great opportunity for everyone to be together, share ideas and develop new collaborations,” she said.