Australian researchers have discovered a ‘switch’ they say tells the body to burn fat.

Scientists at Monash University’s Biomedicine Discovery Institute have found a mechanism by which the brain coordinates feeding with energy expenditure, which could be a new target for anti-obesity treatment.

Feeding controls the ‘browning’ of fat – which is the conversion of white fat, which stores energy, into brown fat, which burns it.

Fat in the human body is stored in specialised cells called adipocytes, which can change from white to brown states and back again.

The new study shows that after a meal the brain responds to circulating insulin, which is increased after a rise in blood glucose. The brain then sends signals to promote the browning of fat to expend energy.

By contrast, after a fast, the brain instructs these browned adipocytes to once more convert into white adipocytes, storing energy.

These processes help prevent both excess weight gain and excess weight loss in response to feeding and fasting, meaning body weight remains relatively stable over time.

The researchers showed that the brain’s ability to sense insulin and coordinate feeding with energy expenditure via browning is controlled by a switch-like mechanism turned on after fasting to inhibit the response to insulin, repressing browning and conserving energy, and turned off after feeding to facilitate the insulin response to promote browning and to expend energy.

“What happens in the context of obesity is that the switch stays on all the time – it doesn’t turn on off during feeding,” lead researcher Professor Tony Tiganis said.

“As a consequence, browning is turned off all the time and energy expenditure is decreased all the time, so when you eat, you don’t see a commensurate increase in energy expenditure – and that promotes weight gain,” Professor Tiganis said.

The researchers are exploring the possibility of inhibiting the switch for therapeutic purposes to promote the shedding of excess fat.

“Obesity is a major and leading factor in overall disease burden worldwide and is poised, for the first time in modern history, to lead to falls in overall life expectancy,” Professor Tiganis said.

“What our studies have shown is that there is a fundamental mechanism at play that normally ensures that energy expenditure is matched with energy intake. When this is defective, you put on more weight. Potentially we may be able to rewire this mechanism to promote energy expenditure and weight loss in obese individuals. But any potential therapy is a long way off,” he said.

The study is accessible here.