May 5, 2008 -- Fat cells may shrink or grow in size, but not in number, a new study shows.
The findings, published in the advance online edition of Nature, hint that it might be possible to create new weight loss drugs that reduce the number of fat cells.
Fat cells (adipocytes) can get bigger or smaller. But the new study isn't about how plump fat cells get. Instead, it's about the number of fat cells that people have.
The researchers -- who included Kirsty Spalding, PhD, of Sweden's Karolinska Institute -- gauged the number of fat cells in 687 adults, and then compared that to past research on the number of fat cells in children and teens.
Obese people had more fat cells than lean people. But the number of fat cells held steady in adulthood, regardless of whether people were lean or obese. When people lost a lot of weight through bariatric surgery, their fat cells shrank in volume but held steady in number.
Next, Spalding's team studied fat cells from 35 people. The fat cells came from fatty tissue collected when the patients had liposuction or abdominal surgery.
The researchers concluded that the fat cells didn't last forever, but died and were replaced by new fat cells at the same rate, resulting in a stable number of fat cells.
Tinkering with that balance so that fat cells aren't replaced as quickly could be a new strategy for weight loss drugs, note Spalding and colleagues.
It's not that you're born with a certain number of fat cells that you keep for life. The number of fat cells rose in kids and teens, leveling off by adulthood, according to the study.