New research emerging from the Garven Institute of Medical Research and the University of NSW has pinpointed the exact brain circuitry that prevents obese people from shedding the excess bodyweight.

Dr Shu Lin, Dr Yanchuan Shi and Professor Herbert Herzog and his team have been studying the complex processes behind energy balance using various mouse models. They have shown that the neurotransmitter Neuropeptide Y (NPY), known for stimulating appetite, also plays a major role in controlling whether the body burns or conserves energy.

The researchers found that NPY produced in a very specific part of the brain – the arculate nucleus (Arc) of the hypothalamus – inhibits the burning of ‘brown fat’, which is known as the heat generator fat.

“This study is the first to identify the neurotransmitters and neural pathways that carry signals generated by NPY in the brain to brown fat cells in the body. It is also the first to show a direct connection between Arc NPY, the sympathetic nervous system and the control of energy expenditure.” said Professor Herzog.  
“We know that NPY also influences other aspects of the sympathetic nervous system – such as heart rate and gut function – but its control of heat generation through brown fat seems to be the most critical factor in the control of energy expenditure.”
“When you don’t eat, or dramatically curtail your calorie intake, levels of NPY rise sharply. High levels of NPY signal to the body that it is in ‘starvation mode’ and should try to replenish and conserve as much energy as possible. As a result, the body reduces processes that are not absolutely necessary for survival.”