Researchers monitored the eating and body composition of groups of mice and rats for a period of four months. They found that those with a neural predisposition to obesity gained 30 per cent more weight compared to six per cent of the group with obesity-resistant cells.
According to MODI director and Australian Life Scientist of the Year Professor Michael Cowley, "We discovered that a high-fat diet caused brain cells to become insulated from the body, rendering the cells unable to detect signals of fullness to stop eating... Secondly, the insulation also created a further complication in that the body was unable to detect signals to increase energy use and burn off calories/kilojoules." The study showed that these brain cells developed overgrowth in a high-fat diet. This prevented the regular brain cells (the melanocortin system or POMC neurons) from connecting with other neural mechanisms, which determine appetite and energy expenditure.
Cowley feels this finding could help curb the obesity epidemic in more ways than one. He said, "These neuronal circuits regulate eating behaviours and energy expenditure and are a naturally occurring process in the brain. The circuits begin to form early in life so that people may have a tendency towards obesity even before they eat their first meal." He added, "Obese people are not necessarily lacking willpower. Their brains do not know how full or how much fat they have stored, so the brain does not tell the body to stop refuelling. Subsequently, their body's ability to lose weight is significantly reduced."
For this study Professor Cowley and fellow MODI researcher Dr Pablo Enriori collaborated with Research Chair and Professor of Comparative Medicine and Professor of Neurobiology Tamas Horvath and his team at the Yale School of Medicine in the United States, together with teams of scientists in Cincinnati, New Jersey, Mexico and Spain.
