Addicted to junk food? It's no joke

Chocolate lovers joke when they call themselves addicts, but science shows they might be right.

An article published today in New Scientist says scientific evidence is building that junk food with high fat, sugar or salt content triggers the same biological mechanisms as those in drug addicts.

Over the past decade, researchers have carried out studies on rats to determine what effects junk food has on the rodents' brain chemistry. Their findings have been backed up by more recent studies on humans.

A 2001 study showed that rats fed a high-sugar diet exhibited withdrawal symptoms when their access to sugar was denied.

A later study found that rats who were allowed to binge on bacon, sausage, chocolate and icing went on a hunger strike for two weeks after their access to those foods was cut off.

In both studies, dopamine – a neurotransmitter that is a key part of the brain's reward system – played an important role.

The rats in the first study experienced a rush of dopamine each time they ate sugar, while the rats in the second study had to eat more and more of the junk food to experience the same dopamine rush. Both effects are factors in drug addiction.

A human study found sugar "addicts" shown their favourite foods experienced a rush of dopamine to the orbital frontal cortex – the same part of the brain that responds when a cocaine addict is shown a bag of white powder.

Researcher Hank Cardello said junk and fast food companies designed their products to have a "high hedonic value" that induced people to eat more.

- © Fairfax NZ News