Get rid of fat cells and more fill in

Northwest Arkansas Democrat-Gazette - - STYLE - ALICE CALLAHAN

Q: Once fat cells form, can you ever get rid of them?

A: The num­ber of fat cells in a per­son’s body seems to be able to change in only one di­rec­tion: up.

The num­ber of fat cells in­creases through child­hood and ado­les­cence and gen­er­ally sta­bi­lizes in adult­hood. But this doesn’t mean that fat cells, or adipocytes, are stag­nant. The size of in­di­vid­ual fat cells is re­mark­ably vari­able, ex­pand­ing and con­tract­ing with weight gain or weight loss. And as with most cell types in the body, adipocytes die even­tu­ally.

“Usu­ally when old ones die, they are re­placed by new fat cells,” said Dr. Michael Jensen, an en­docri­nol­o­gist and obe­sity re­searcher at the Mayo Clinic. Cell death and pro­duc­tion ap­pear to be tightly cou­pled, so al­though about 10 per­cent of adipocytes die each year, they’re re­placed at the same rate.

Even among bariatric surgery pa­tients, who can lose a lot of weight, the num­ber of fat cells tends to re­main the same, al­though they shrink in size.

Li­po­suc­tion re­duces the num­ber of fat cells in a per­son’s body, but stud­ies show the weight lost is typ­i­cally re­gained within a year. It isn’t known whether this re­gain oc­curs through the pro­duc­tion of new fat cells or ex­pan­sion of ex­ist­ing ones.

Peo­ple who are obese tend to have more fat cells than those who are not, and sev­eral stud­ies have found an in­crease in fat cells with weight re­gain fol­low­ing weight loss.

The fact that fat cells can be in­creased but not de­creased most likely con­trib­utes to the body’s drive to re­gain weight af­ter weight loss, said Dr. Kirsty L. Spald­ing, a cell bi­ol­o­gist at the Karolin­ska In­sti­tute in Swe­den and the lead au­thor of a 2008 study show­ing that fat cells die and are re­placed. Be­yond their role in stor­ing fat, adipocytes se­crete pro­teins and hor­mones that af­fect en­ergy me­tab­o­lism.

“Fol­low­ing weight loss, adipocytes be­come smaller, gen­er­ally smaller than those from peo­ple with a sim­i­lar BMI,” Spald­ing said. One hy­poth­e­sis is that those smaller cells might send sig­nals to in­crease ap­petite and fat stor­age, which could help to ex­plain why weight loss is so dif­fi­cult to main­tain, though much more re­search is needed.

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