Last year, researchers made a game-changing realization: brown fat, the
energy-burning stuff that keeps babies warm, isn't just for the
youngest among us. Adults have it, too (if they are lucky, anyway), and
it is beginning to look like the heat-generating tissue might hold
considerable metabolic importance for familiar and irritating trends,
like our tendency to put on extra weight as we age. If we can find a
way to hold onto, make more, or activate brown fat, it might be one way
to help keep us slim, according to scientists who have written a series
of minireviews appearing in a special April issue of Cell Metabolism, a Cell Press journal.
"It's a new metabolic world; we can now ask questions we wouldn't have
considered even one year ago," says Jan Nedergaard of Stockholm
University, who authored one of the five reviews.
Brown fat was once the preoccupation of a few researchers
studying rodents and newborn mammals. "At times, their work was deemed
more an exercise in scientific curiosity than an issue relevant to
human health," write Cell Metabolism editors Nikla Emambokus and Charlotte Wang in an editorial.
That all changed when three papers in the New England Journal of Medicine
showed that adults have brown fat cells in their necks, where, as Sven
Enerbäck of Göteborg University explains, it has the unique ability to
safely dissipate chemical energy in the form of heat. When we spend a
lot of time in the cold, the amount of brown fat we have goes up.
