Scientists in Ottawa have discovered a molecular switch for the creation of fat cells in mice.

The researchers found a pathway that determines how an immature cell becomes one of two types of fat.

White fat is the storage deposits that mammals burn for energy when food supplies run low. Brown fat, found around internal organs and between the shoulder blades, is burned to generate heat.

Michael Rudnicki.

Michael Rudnicki of the University of Ottawa studied laboratory mice with half the fat of normal mice and more brown fat.

The team found if a mouse has a gene called p107, it makes white fat and becomes fat. If it does not have the gene, the mouse produces brown fat and is skinny, the team reports in Tuesday's issue of the journal Cell Metabolism.

The researchers say understanding how the gene works is the first step towards creating drugs to make people thinner and help control obesity, although drugs based on the findings are at least 10 years off.

"Because we understand what the mechanism is, we can rationally design drugs or other treatments to control the differentiation of those cells," said Rudnicki.

Scientists don't fully understand how white fat changes into brown fat in mice, a process that is probably more complicated in humans.