New research by US scientists will strengthen evidence that junk food is addictive and that prolonged consumption turns fast food eaters into junkies.

It has already shown that many commonly eaten junk foods can become a substitute for happiness. The latest research will show just how dangerous the junk food addiction can be.

The soon to be published study by Paul Kenny and his team at Florida’s Scripps Research Institute found that a diet of burgers, chips, sausages and cake will programme the brain into craving even more foods that are high in sugar, salt and fat.

The Scripps team fed rats either healthy food, a diet containing restricted amounts of junk food or a diet with unlimited amounts of junk food.  They found that the rats that ate as much junk food as they wanted quickly became very fat and started bingeing. There were no adverse effects on those fed the other diets. 

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

After just five days the bingeing rats showed “profound reductions” in the sensitivity of their brains’ pleasure cells. They had quickly become used to the unhealthy food and, although they didn’t need it, ate more to make themselves feel happy.

The Scripps team believe theirs is one of the first studies to demonstrate brains may react in the same way to junk food as they do to drugs.

“This is the most complete evidence to date that suggests obesity and drug addiction have common neuro-biological foundations,” said Paul Johnson, a member of Kenny’s team told the Daily Express. He added: “You lose control. It’s the hallmark of addiction,” he said.