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Obesity: is infection the villain? Or the brain?

The study by University of California-San Diego researchers supporting the theory that obesity may have an infectious origin reported in Pediatrics has been challenged by another study by an influential international collaboration involving Australian researchers. The later study - published in Proceedings of National Academy of Sciences (PNAS) - reports on animal research finding that a high fat diet causes brain cells to become insulated from the body, preventing it from receiving signals that tell it to stop eating and to burn energy.

01 Nov 2010

The study by University of California-San Diego researchers supporting the theory that obesity may have an infectious origin reported in Pediatrics has been challenged by another study by an influential international collaboration involving Australian researchers.

The later study - published in Proceedings of National Academy of Sciences (PNAS) - reports on animal research finding that a high fat diet causes brain cells to become insulated from the body, preventing it from receiving signals that tell it to stop eating and to burn energy.

The PNAS research shows that support cells in the brain developed over-growth in a high-fat diet. This prevented the regular brain cells (the melanocortin system, or POMC neurons) from connecting with other neural mechanisms that determined appetite and energy expenditure.

The animal study was led by the Monash Obesity and Diabetes Institute (MODI) at Monash University, collaborating with researchers at the Yale School of Medicine, University of Cincinnati, New Jersey University of Medicine and Dentistry, Universidad Autónoma de Madrid and the German Institute of Human Nutrition.

Over four months, the researchers monitored the eating and body composition of groups of mice and rats, finding that those with a neural disposition to obesity gained 30% more weight compared to 6% in those with obesity-resistant cells.

Prof Michael Cowley of MODI (and Australian Life Scientist of the Year) said that eating a high-fat diet caused more ‘insulation’ in the nerve cells and made it harder for the brain to help a person to lose weight.

“Obese people are not necessarily lacking willpower,” he said. “Their brains do not know 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.”

 


Published: 01 Nov 2010