Scientists at the University of British Columbia have discovered what they believe to be a key gene that causes obesity.

The gene, which encodes a protein called 14-3-3ζ (zeta), is found in every cell of the body. But when switched off, it resulted in a 50 percent reduction unhealthy "white fat" — associated with obesity, heart disease, and diabetes — in mice studied by the BC researchers, Medical Xpress reports.

The fat reduction occurred despite the mice consuming the same amount of food, the researchers reported in the journal Nature Communications.

They added that the study points the way to a possible gene-drug therapy to combat obesity.

"People gain fat in two ways — through the multiplication of their fat cells, and through the expansion of individual fat cells," said Gareth Lim, a postdoctoral fellow in UBC's Life Sciences Institute. "This protein affects both the number of cells and how big they are, by playing a role in the growth cycle of these cells."

Obesity is linked to diabetes, heart disease, and some forms of cancer. Worldwide, obesity-related costs add up to $2 trillion each year, experts say.