Source: Natural News
A diet including unlimited amounts of junk food can cause rats to become so addicted to the unhealthy diet that they will starve themselves rather than go back to eating healthy food, researchers have discovered.
In a series of studies conducted over the course of three years and published in the journal Nature Neuroscience, Scripps Florida scientists Paul Johnson and Paul Kenny have shown that rats’ response to unlimited junk food closely parallels well-known patterns of drug addiction — even down to the changes in brain chemistry.
“What we have are these core features of addiction, and these animals are hitting each one of these features,” Kenny said.
In their first study, the researchers fed rats on either a balanced diet or on the same diet plus unlimited access to junk foods purchased at a local supermarket, including processed meats and cakes. Within a short time period, the rats on the junk food diet began to eat compulsively and quickly became overweight.
“They’re taking in twice the amount of calories as the control rats,” Kenny said.
The researchers hypothesized that the rats were eating compulsively because, like drug addicts, they had become desensitized to smaller amounts and needed more and more for the same rush of pleasure.
“They lose control. This is the hallmark of addiction.”
In another test of their addiction hypothesis, the researchers used a virus to block the D2 receptors in healthy rats. All those rats soon became compulsive eaters.
“This is the most complete evidence to date that suggests obesity and drug addiction have common neurobiological underpinnings,” Johnson said.
Having established that the junk food rats had become addicted, Johnson and Kenny wanted to know how far this addiction would push them. So they took both junk-food addicted rats and rats that had not previously been exposed to such food, and exposed them to electrical shocks whenever they ate junk. Rats that had just been introduced to junk food quickly stopped eating it, while the addicted rats ignored the discomfort and kept eating.
Perhaps the most shocking finding came when the researchers took away the addicted rats’ access to junk food and started feeding them only healthy rat chow again — the same diets the rats had eaten as pups. When junk food was no longer available, the rats simply refused to eat for two weeks.
“They actually voluntarily starved themselves,” Kenny said.
“It’s almost as if you break these things, it’s very, very hard to go back to the way things were before. Their dietary preferences are dramatically shifted.”
“The rats don’t suffer from the same social pressures that we do,” he said.
“Certainly, we see this addictive pattern in humans,” nutritionist Sandy Livingston said. “They know they shouldn’t overeat, but they do it anyway.”
“Food can be highly addictive,” said author and nutritional supplement producer Jordan Rubin.
He called for more research into which individual components of junk food, such as MSG, might be behind its addictive effects.
“They might be a normal weight, but how they respond to food in the future may be permanently altered,” he said.
Johnson and Kenny’s research was funded by grants from the National Institutes of Health, Bank of America and The Margaret Q. Landenberger Research Foundation.
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