The Number of Fat Cells Remains Constant in All Body Types
The radioactive carbon-14 produced by above-ground nuclear testing in the 1950s and '60s has helped researchers determine that the number of fat cells in a human's body, whether lean or obese, is established during the teenage years. Changes in fat mass in adulthood can be attributed mainly to changes in fat cell volume, not an increase in the actual number of fat cells....
A new study by Lawrence Livermore National Laboratory scientist Bruce Buchholz - along with colleagues from the Karolinska Institute in Sweden; Humboldt University Berlin, Foundation of Research and Technology in Greece; Karolinska University Hospital; and Stockholm University - applied carbon dating to DNA to discover that the number of fat cells stays constant in adulthood in lean and obese individuals, even after marked weight loss, indicating that the number of fat cells is set during childhood and adolescence....
In the new study, Buchholz analyzed the uptake of carbon-14 in genomic DNA within fat cells to establish the dynamics of fat cell turnover. Approximately 10 percent of fat cells are renewed annually at all adult ages and levels of body mass index.
Neither fat cell death nor its generation rate is altered in early onset obesity, suggesting a tight regulation of the number of fat cells in obese adults.
"Fat cells change in size but no one had ever measured fat cell turnover," Buchholz said. "An increase in cell size means it can hold more mass."