HPC-UK Bitesize (Fat Loss): Why Dieting Doesn’t Work; Brain Circuits

We all know that common approaches to dieting don’t work. This is partly because they are, no matter how they wrap it up, still based on the overly simplistic and erroneous notion of ‘calorie balance'. It’s a lot more complicated than that, and if you go down that path, then you’ll continually struggle to control your weight (fat). A new piece of research has given us a glimpse into one mechanism that is part of this problem.

Imagine you are driving a car, and the harder you press on the accelerator, the harder an invisible foot presses on the brake. That's what happens when people diet – the less food they eat, the less energy they use, and the less fat they lose.

Neuropepetide Y (NPY) is best known for its powerful stimulation of food intake and its effects on reducing energy expenditure; this has been known for a good while now, but we didn’t quite know how it worked. Now thanks to the scientists at Sydney's Garvan Institute of Medical Research and the University of NSW we have a better understanding.

When you don't eat, or dramatically curtail your energy 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. In a nutshell, your hunger drive goes into overdrive, your heat output is reduced and your libido and general energy levels get pummelled.

The researchers found that NPY produced in a particular region of the brain called the ‘arcuate nucleus (Arc) of the hypothalamus’ inhibits the activation of 'brown fat', one of the primary tissues where the body generates heat (*see links below). 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.

Reference:

Yan-Chuan Shi et al. Arcuate NPY Controls Sympathetic Output and BAT Function via a Relay of Tyrosine Hydroxylase Neurons in the PVN. Cell Metabolism, Volume 17, Issue 2, 236-248, 5 February 201

* http://humanperformanceconsulting-uk.blogspot.co.uk/2011/11/hpc-uks-top-tips-for-fat-loss-tip-no9.html

* http://humanperformanceconsulting-uk.blogspot.co.uk/2012/01/ive-got-chills-theyre-multiplying.html