Scientists have found the brain’s “on switch” for burning fat.
The discovery could lead to a huge breakthrough in treating obesity, which is reaching epidemic levels.
The new study helps solve the puzzle of how the body chooses to burn or store fat, and how it makes use of the energy from food that people eat.
Scientists looked specifically at how the body converts white fat, which stores energy, into the brown fat that is used to burn it. Fat is stored in special cells that are able to change from brown to white, and so help the body burn or keep the energy it eats.
They found that when a person eats, the body responds by circulating insulin. The brain then sends out signals to encourage the browning of fat, so that it can expend energy.
Likewise, when someone is not eating or is fasting, the brain sends instructions to the special cells known as adipocytes telling them to turn fat white. That helps store the energy when people aren’t eating, and makes sure that a person’s body weight stays stable.
That complex process is controlled by a switch-like mechanism in the brain. It switches itself off and on according to whether a person has eaten, and helps regulate how the body uses fat.
But in obese people, the switch doesn’t seem to work properly – it gets stuck in the on position. When people eat, it doesn’t turn to off – and so energy isn’t expended.
“What happens in the context of obesity is that the switch stays on all the time – it doesn’t turn on off during feeding,” said lead researcher Tony Tiganis, from Monash University’s Biomedicine Discovery Institute.
“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.”
Now the scientists hope they can manipulate the switch, turning it off and on to help people better control how their body deals with 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,” Mr Tiganis said in a statement.
“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.