Study outlines science behind diet failures

June 4th, 2008 - 2:58 pm ICT by IANS  

Washington, June 4 (IANS) Why do some diets fail? A new study says it is because what we eat does not really decide how thin or fat we are. At one level, fat accumulation is a relatively simple process involving excess energy intake and too little expenditure — yet the physiology of it is quite complex, according to Kaveh Ashrafi of the University of California

Ashrafi and his colleagues set out to understand this complexity using the worm C. elegans, an organism that is much simpler to work with in comparison to mammals.

It is well known that feeding patterns and fat formation are both dependent on the levels of serotonin - a nerve messenger - in the nervous system.

But the new study has found evidence that serotonin acts through one channel to decide what (and when) you eat - and through another to decide what to do with the calories.

Explained Ashrafi: “The nervous system makes a decision about its state leading to effects on behaviour, reproduction, growth and metabolism. These outputs are related, but they are not consequences of each other.

“It’s not that feeding isn’t important, but the neural control of fat is distinct from feeding.”

If the results in worms are extrapolated to humans, then the finding may have clinical implications.

“From a clinical perspective, this may mean you could develop therapeutic strategies to manipulate fat metabolism independently of what you eat,” he said.

“Now, the focus is primarily on feeding behaviour. As important as that is, it’s only part of the story. If the logic of the system is conserved across species, a strategy that focuses solely on behaviour can only go so far. It may be one reason diets fail.”

The findings of the study have been published in the latest issue of the journal Cell Metabolism.

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