Yale: Once fat cells form, they might shrink during weight loss, but they
do not disappear, a fact that has derailed many a diet. Yale researchers
in the March 2 issue of the journal Nature Cell Biology describe how, and just how quickly, those fat cells are created in the first place.
Young
mice fed an obesity-inducing diet fail to produce fat cells if they
lack a key pathway involved in the sensing of nutrients, the study
showed. In addition the new study also revealed that fat cell production
starts within a day of starting a high-fat diet.
“In studying
what happens before these animals become obese, we found that this
fat-producing response occurs unbelievably quickly,” said Matthew
Rodeheffer, assistant professor of comparative medicine and of
molecular, cellular, and developmental biology, and senior author of the
paper.
Weight gained is caused by the creation and expansion of
white fat cells, or adipose tissue. Dieting can shrink fat cells but not
eliminate them, which is why people can gain weight back so quickly.
The Yale team found that the activation of a nutrient signaling pathway
called PI3-kinase/AKT-2 was necessary to produce fat precursor cells,
which in turn produce adipose tissue. Normal mice began producing these
precursor cells within 24 hours of starting a high-fat diet.
Rodeheffer
stressed that this pathway has other key functions, such as glucose
regulation, and probably cannot be safely targeted in people.
“However,
it may be possible to inhibit the generation of more fat cells in
obesity and increase our understanding how dietary changes drive
increased fat mass,” he said.
Primary funding for the work was provided by the National Institutes of Health.
Other Yale authors are Elise Jeffery, Christopher D. Church, Brandon Holtrup, and Laura Colman.