• "...Overeating and obesity is really an addiction-like disorder." (AAP)
A new Australian-led study has shown that a person who becomes obese because they ‘overeat’ may actually have a clinical addiction to food that is high in fat and sugar.
By
Yasmin Noone

27 Jan 2016 - 4:34 PM  UPDATED 28 Jan 2016 - 4:39 PM

An obese person who compulsively overeats may be clinically addicted to food that is high in sugar and fat in the same way that a drug addict is addicted to cocaine, a new Australian-led study has found.

The world-first study, published in the journal Biological Psychiatry today, draws similarities between the brain patterns of obese and drug addicted mice.

It also suggests that the brain processes behind drug addiction and obesity caused by compulsive overeating are also similar in humans. 

"What we are saying is that there is a predisposition in some of us to overeat, which is similar to what we see with drug addiction," says the study’s lead researcher lead, Dr Robyn Brown from the Florey Institute of Neuroscience and Mental Health.

Dr Brown explains that an obese individual who compulsively overeats knows they should stop eating and lose weight to improve their health and even save their own life. But, just like a drug addict, they won’t be able to help themselves and continue to eat a diet rich in sugar and fat.

"What we are saying is that there is a predisposition in some of us to overeat, which is similar to what we see with drug addiction."

"To me, being an addiction neuroscientist, that’s a real telling sign that for some people, overeating and obesity is really an addiction-like disorder.

"And in some ways, it’s also sort of insulting to tell an obese person who overeats just to eat less and exercise more."

The findings come as good news for the millions of obese people around the world who have battled against the scales for years but have never been able to overpower their urge to overeat.

"We know that there are pharmacological therapies that work in drug addiction. These therapies will be tested to see if they work for overeating.

"The good news is that these drugs are already approved and on the market so if they do work on people who overeat, we can get them out sooner."

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Dr Brown, a Peter Doherty Research Fellow, worked with researchers from Monash University and the Medical University of South Carolina to test the theory of addiction on obese rats.

To do this, the team initially fed a group of vermin a diet rich in fat and sugar. Much like humans, only one third of them went on to develop obesity caused by overeating.

They then compared the brains of the obese rats to rats which remained a healthy weight.

Brain changes observed included an inability to regulate eating behaviour, with the obese animals chowing through almost 60 per cent more food that their healthier counterparts, and brain activity changes associated with reward seeking.

This brain region, called the Nucleus Accumbens, was 'hijacked' by addictive substances, and the animals in this study showed the same brain changes seen in animals addicted to cocaine.

It is yet to be determined why some rats seemed predisposed to overeating and addiction and other rats maintained control.

"Not everyone who uses drugs will become an addict: it’s the same thing with food. Not everyone exposed to food that’s high in fat and sugar, will become addicted."

"The good news is that these drugs are already approved and on the market so if they do work on people who overeat, we can get them out sooner."

Dr Brown concedes that these food addiction findings only apply to a third of all obese individuals, who compulsively overeat. Meanwhile, two thirds of all obese people are thought to be overweight because of poor food choices, exercise and lifestyle issues.

She therefore advises people who have issues with overeating to consider psychological and medical support to break a cycle of food addiction and maintain a healthy weight.

"Society judges people who are obese quite harshly. But people with obesity need to say ‘hang on. I could have what is more like an eating disorder.

"If someone thinks they have a problem, they need to try and seek some help."

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