Training body to burn fat, not store it

Researchers have uncovered a new molecular mechanism for stimulating the body to burn fat -- a discovery that could lead to new medications to fight obesity, diabetes and heart diseases.

By knocking out the gene that produces a protein, known as folliculin, in fat cells in mice, the researchers triggered a series of biomolecular signals that switched the cells from storing fat to burning it.

This process is known as the 'browning' of fat cells. The principal role of brown fat is to burn energy to produce heat, which helps keep our body temperature constant. White fat serves as an energy-storage tissue.

Scientists recently discovered a new type of fat tissue with characteristics somewhere between healthy brown fat and the not-so-healthy white kind. The so-called beige fat is capable of behaving like brown fat in response to certain stimuli such as exposure to cold.

"Conversion from white fat cells to beige or brown fat cells is a very desirable effect in the obesity, diabetes, and metabolic syndrome indications, since excess energy in the body is not stored in fat tissue but is burned in brown or beige fat tissue," said the study's senior author Arnim Pause, professor at McGill University in Montreal, Canada.

For the study, published in the journal Genes & Development, the team bred mice to have fat cells that did not produce folliculin. They then fed normal mice and folliculin-deficient mice with a high-fat, junk food-like diet over 14 weeks.

Normal mice gained weight rapidly, whereas folliculin-deficient mice remained slim.

By measuring rates of oxygen consumption and CO2 production, the researchers found the folliculin-deficient mice were burning more fat.

At the end of the trial, these mice had smaller white fat cells and less white fat tissue overall.

The extra energy they were producing made them better at tolerating cold temperatures, too, the researchers said.

The research could open the way for new medications to be developed that will stimulate the 'browning' process.

"One implication (of the study) is that a drug could be developed to stimulate the activity of beige/brown fat cells and thus help manage obesity and other metabolic disorders," Vincent Giguere from the University in Montreal noted.