Senin, 26 Desember 2011

The Secret of Why Diets Don’t Work

Revealed! The secret of why Diets don’t work

IF YOU are on a diet and are frustrated that it is not working well, here is some food for thought. The reason behind difficulty in sticking to a diet plan may lie in strange behaviour of brain cells that regulate appetite, latest research has revealed.

"When we don’t eat, hunger-inducing neurons in the brain start eating bits of themselves. This act of self-cannibalism turns up a hunger signal to prompt eating,” says research to be published in the August issue of journal Cell Metabolism.

The process uncovered by scientists in neurons of the brain’s hypothalamus region is known as autophagy or self-eating. It occurs in other parts of the body as a way of providing energy in times of starvation but scientists so far had believed the brain to be relatively resistant to starvation-induced autophagy.

The new finding means that it may be possible in future to develop a drug that blocks this process, enabling people to diet as they wish.

Self-eating generates free fatty acids in brain cells called agouti-related peptide.

These fatty acids in turn boost levels of these neurons which are a hunger signal themselves, explained Dr Rajat Singh, an Indiaborn and educated scientist who led the research team at the Albert Einstein College of Medicine. When the process of self- eating is blocked in the neurons, their levels fail to rise in response to starvation.

“ We have shown that starvation activates autophagy in hypothalamic neurons. This process breaks down fat stores in brain cells, liberating free fatty acids. The increased availability of free fatty acids inside these brain cells increases levels of a hunger- generating molecule, agouti-related peptide,” Singh said.

The findings were tested in transgenic mice engineered to lack hypothalamic neurons.

These transgenic mice ate less food in response to a fasting challenge, and were leaner with less abdominal fat when compared to mice with functional autophagy.

"Decreased body weights of transgenic mice occurred in part from decreased food intake, and in part from increased physical activity,” Singh explained.

Chronic overeating contributes to obesity, and its typical effects like diabetes.

"We found that blocking autophagy in agouti- related peptide neurons decreases the amount of food consumed, as well as increases physical activity — all of which contribute to preventing obesity and inappropriate fat accumulation in the body,” Singh said.

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