Junk food may be addictive in the same way as heroin or cocaine, according to a study showing that laboratory rats will endure painful electric shocks to satisfy their craving for high-calorie snacks made from sausages, bacon and cheesecake.
Scientists have found that a “café-style” diet of fatty, sugary food results in compulsive overeating among rats and causes neuro-chemical changes to the brain that mimic the sort of alterations in the human brain brought about by addiction to heroin and cocaine.
The findings lend support to the idea that certain types of energy-intensive foods can trigger compulsive overeating and obesity in humans, leading to a form of food addiction that is almost impossible to overcome by dieting.
The researchers found that rats offered junk food quickly became so attached to it that they would endure painful but harmless electric shocks to their feet in order to eat it. They would even prefer to starve themselves rather than eat the “salad bar option” of the typical rodent food eaten by rats that had never had junk food.
When the scientists analysed the brains of the junk-food rats they found that a key pleasure-reward system known to be involved in triggering drug addiction in humans was overstimulated, causing the animals to eat more and more food in order to enjoy the same chemical “high” felt in their brains.
“It presents the most thorough and compelling evidence that drug addiction and obesity are based on the same underlying neurobiological mechanisms,” said Professor Paul Kenny at the Scripps Research Institute in Jupiter, Florida.
“The animals completely lost control over their eating behaviour, the primary hallmark of addiction.”