A faulty brain 'switch' may be responsible for immoderate weight gain, a new study shows.
According to 2014 data from the World Health Organization (WHO), more than 600 million adults around the globe are obese, and 41 million children younger than 5 years old are overweight.
In the United States, 36.5 percent of the adult population, as well as around 17 percent of children and adolescents, have obesity. A study recently covered by Medical News Today referred to exacerbated weight gain as a "pandemic" affecting the U.S. and wider world.
This situation is particularly concerning because, according to the Centers for Disease Control and Prevention (CDC), excess weight can impact other health aspects, leading to high blood pressure, diabetes, coronary heart disease, and depression.
In light of this, a team of researchers from the Biomedicine Discovery Institute at Monash University in Melbourne, Australia, has recently conducted a study striving to gain a better understanding of the brain mechanisms that contribute to weight gain and loss.
Lead researcher Prof. Tony Tiganis and first author Dr. Garron Dodd revealed the existence of a "switch" that tells the body what to do with the fat gained after food intake. If the switch is faulty, they say, then the body is likely to store more fat, thus becoming predisposed to obesity.
These findings are published in the journal Cell Metabolism.
The Metabolic Disease & Obesity program of the Biomedicine Discovery Institute, which is led by Prof. Tiganis, has found a link between food intake and the process whereby white fat turns into brown fat.
In the body, fat is stored in adipocytes, or cells that make up the adipose tissue. These fat cells can convert from "white" (storing energy) into "brown" (releasing energy).
Faulty brain 'switch' determines obesity
The study found that the brain normally "instructs" the white fat cells to turn into brown ones after eating. This comes in response to insulin released into the bloodstream in larger quantities as blood glucose, or blood sugar, levels increase.
On the other hand, brown fat cells are turned back into white energy-storing fat cells after a period of abstinence, during which no food is consumed. When this mechanism functions normally, it allows the body to stabilize its weight, preventing excessive gain - or loss - of fat.
This mechanism, say the researchers, is akin to a switch, "reading" the insulin signals and flipping on and off as appropriate. In the case of people predisposed to excess weight gain, this switch malfunctions, becoming stuck in the "on" position.
"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."
Prof. Tony Tiganis
The scientists' new findings further elucidate the implications of the brain's response mechanism in the context of obesity.
"For a long time, the missing piece to the puzzle was always why this [browning of white fat cells] occurs in the body. We've shown not only why this occurs but also the fundamental mechanism involved. It's very exciting," says Dr Dodd.
What Dr. Dodd and Prof. Tiganis hope to do next is learn whether or not the switch can be determined to "tell" the body to get rid of more fat in the case of excess weight gain.
"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," concludes Prof. Tiganis.