American researchers found burgers, chips and sausages programmed a human brain into craving even more sugar, salt and fat laden food.

Scientists at the Scripps Research Institute in Florida found laboratory rats became addicted on a bad diet just like people who became dependent on cocaine and heroin.

The study suggests for the first time that our brains may react in the same way to junk food as they do to drugs. Photo: PA

While the findings cannot be directly transferred to human obesity, it found that overconsumption of high-calorie food triggered addiction-like responses in the brain.

But the study, published online in Nature Neuroscience, suggests for the first time that our brains may react in the same way to junk food as it does to drugs.

Dr Paul Kenny, a neuroscientist who led the research, said the study, which took nearly three years to complete, confirmed the "addictive" properties of junk food.

"Obesity may be a form of compulsive eating,” he said.

“Other treatments in development for other forms of compulsion, for example drug addiction, may be very useful for the treatment of obesity.

"The new study explains what happens in the brain of these animals when they have easy access to high-calorie, high-fat food.”

He added: "It presents the most thorough and compelling evidence that drug addiction and obesity are based on the same underlying neurobiological mechanisms.”

In the study, the research team divided the animals into three groups.

One got normal amounts of healthy food to eat, another was given restricted amounts of junk food and the third had unlimited amounts of cheesecake, fatty meat products, cheap sponge cakes and chocolate snacks.

There were no adverse effects on the first two groups. But the rats which ate as much junk food as they wanted quickly became very fat and started bingeing.

When researchers electronically stimulated the part of the brain that feels pleasure, they found the rats on unlimited junk food needed even more stimulation to register the same level of pleasure as the animals on healthier diets.

"They always went for the worst types of food and as a result, they took in twice the calories as the control rats,” said Dr Kenny.

"When we removed the junk food and tried to put them on a nutritious diet – what we called the 'salad bar option' – they simply refused to eat.

"The change in their diet preference was so great that they basically starved themselves for two weeks after they were cut off from junk food."

Dr Kenny said the research supported what obese patients have been saying for years that, like addiction to other substances, junk food bingeing is extremely difficult to stop.

In the rats, the development of obesity coincided with a progressively deteriorating chemical balance in the circuitry of the brain responsible for reward.

As these pleasure centres become less and less responsive the animals quickly develop compulsive overeating habits, consuming larger quantities of high-calorie, high-fat foods until they become obese.

The very same changes occur in the brains of rats that over consume cocaine or heroin, and are thought to play an important role in the development of compulsive drug use.

The scientists fed the rats a diet modelled after the type that contributes to human obesity easy to obtain high-calorie, high-fat foods. Soon after the experiments began, the animals began to bloat.

Latest figures show that one in four people in Britain are obese with married people twice as likely to become obese than their single counterparts.

Eight in 10 men and almost 7 in 10 women will be overweight or obese by 2020.

Cases of devastating health conditions like heart disease, diabetes and stroke will increase with the nation’s waistlines, the recent Government-commissioned Foresight report warned.

www.telegraph.co.uk/health/healthnews/7533668/Junk-food-as-addictive-as-heroin-and-smoking.html

March 29, 2010