Subjects: R and D
Scientists have known for 3 decades that brown fat acted like a furnace in mice, burning calories, generating heat and producing weight loss when stimulated by prolonged exposure to cold temperatures.
They also knew that human infants had a pretty good stock of these mitochondria-leaden cells, but they couldn’t find it in adults, and had assumed it disappeared as a byproduct of normal human development.
Now, scientists armed with PET scanners in 3 laboratories have found the stuff in adults, raising hope we can one day turn it on and trigger weight loss as a result.
The trio of studies appears in the New England Journal of Medicine.
The studies revealed that the quantity of brown fat tended to be higher in females and those who were thin, young, and had lower fasting blood glucose levels. It was lower in those taking beta blockers.
In the first study, Aaron Cypess and colleagues at Harvard reviewed over 1,000 PET scans performed for various reasons to localize brown fat deposits in adults. It turned up in unexpected locations like the side of the neck, upper back and near the spine and collarbone.
In the second study of 24 healthy male volunteers, van Marken Lichtenbelt and colleagues at Maastricht University showed that PET scans turned up negative for brown fat until subjects were placed in a chilly room for a few hours. Retesting the chilled subjects revealed brown fat in all but one.
This phenomenon was confirmed in a third study of 5 healthy adults by Vertanin and colleagues at the University of Goteborg.
The scientists now want to lean more about how to activate brown fat, and determine whether people would respond to such a provocation by simply eating more, which would pretty much nullify any beneficial effects.