Rats reveal key to candy craving

19 December 2008

If your sweet tooth gets the better of you this Christmas, don't be too hard on yourself. After years of study, scientists can now officially say that sugar is addictive - at least in rats. Antenna keeps things sweet...

Many people claim they are addicted to sweet foods.

Image: iStockphoto

Bingeing, withdrawal, and craving are the three key signs of addiction. American scientists have now shown that sugar ticks all three boxes in rats.

To get rats hooked on sugar, scientists deprived the rodents of food for several hours and then allowed them to gulp down sugary water.

Image: Johannes Hloch/iStockphoto

In the team's latest experiment, they found that sugar-loving rats gobble up extra sweet stuff to satisfy their sugar craving after being forced to go cold turkey.
Until now, the researchers had only seen evidence of bingeing and withdrawal. Proof that sweet-toothed rats also crave sugar is the final piece in the puzzle confirming that sugar can be addictive.

Rats addicted to sugar suffer withdrawal symptoms if they go without their daily sweet-fix - their teeth chatter and they hide themselves away.

Image: Achim Prill/iStockphoto

The researchers also found that sugar-loving rodents are susceptible to other forms of addiction. In experiments where the rats had their sugar taken away, they drowned their sorrows and binged on alcohol instead.
When the scientists looked at the rats' brains they found major changes, including high levels of a chemical called dopamine. This closely resembles the effects of addictive drugs such as cocaine and heroin.

Addictive drugs release dopamine in the brain.

What's going on in the rats' brains?
Brains have evolved so we seek things that the body needs, such as food. But if the chemicals in our brains that control these desires are out of balance, it can lead to harmful, addictive behaviour.

Image: Tim Child

So what do these findings mean for us?
'We have the first set of studies that suggest rats really do become addicted to sugar and a mechanism that might underlie it.' Bart Hoebel, lead researcher
'It seems possible that the behaviours and brain changes that we've seen in rats may occur in some people with eating disorders. This knowledge might help us to devise new ways of diagnosing and treating addictions in people.'
What do other experts think?
'This is very interesting research. However, it's important to note that the findings show that sugar is only addictive under very specific conditions. It wasn't addictive when the rats consumed it throughout the day, only when they were forced to binge.' Chris Chandler, addiction expert
'This means that sugar might only be addictive to a very small group, like people with bulimia, and not important for people who are obese because they consume too many calories.'

Image: Ryan Kelly/iStockphoto

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