Meet Brown Fat
By Mary_RD on Apr 23, 2009 12:00 PM in Dieting & You
Brown fat is a major calorie burner. It might be the reason why some people eat and stay slim, while others eat and get fat.
Brown fat was in the news last week. You know you’re a nutrition wonk if you honk for brown fat.
How now brown fat
A quick lesson about fat in the body (not the fat in food you eat): there are two kinds of fat tissue - white fat and brown fat. The more familiar white fat stores potential energy. White fat is ultimately broken down to ATP (stay with me), the form of energy used by the body.
Brown fat, on the other hand, provides immediate energy by burning calories to generate heat. You’ve heard of solar energy, wind energy, and energy from fossil fuels? Brown fat is direct energy too. (Brown fat is “brown” because it contains iron-rich enzymes that are lacking in white fat.)
Brrr!
Brown fat cells become active and grow when exposed to the cold. For instance, hibernating animals grow and burn brown fat for heat during the winter.
Newborn humans also make brown fat to protect against the cold. Infants don’t shiver because their brown fat keeps them warm. Brown fat was thought to disappear after infancy, but last week, three groups of scientists published research showing that humans can generate brown fat all life long.
The scientists stimulated brown fat production by keeping their research subjects very cold. Two groups stuck their subjects in extra chilly rooms and one group submerged the subjects’ tootsies in an ice-water bath. After a few hours, the research subjects produced significant amounts of brown fat. It showed up as bursts of light in the neck and upper back when imaged by a PET (Positron Emission Tomography) scan.
Sure enough, as for hibernating animals, brown fat is there to warm humans in extreme cold.
What if….
An absence of brown fat predisposes a person to obesity. Obese people might have less brown fat than normal weight folks do. Or maybe the brown fat of obese people produces less heat. Or brown fat might burn up an excess calories for slim people, instead of storing them as white fat.
The point is that if scientists can get a handle on brown fat, perhaps they can activate it to burn calories. Turn extra calories into heat. Global warming and obesity - killed with just one stone!
But until them, there’s no real reason to think about brown fat, except to know our furry friends are warm. Meanwhile, bring on that blast of AC and forget to leave your sweater at home.
Your thoughts….
Is brown fat cool?
