Are you a carb addict?

By Jerome Burne for MailOnline
Updated: 04:31 EST, 9 January 2009

Moreish: Some treats could be addictive, say scientists

Could it really be that sweets and chocolate are as addictive as cigarettes?

That's the controversial conclusion from a study by New Zealand scientists who found that foods made largely from refined sugar and flour have the same addictive qualities as tobacco.

'Heavily processed carbohydrates such as cornflakes, sweets and croissants quickly raise the amount of sugar in your blood,' explains lead researcher Dr Simon Thornley, a registrar with the Auckland Regional Public Health Service.
'This rush of sugar stimulates the same areas of the brain that are involved with addiction to nicotine and other drugs.'

In other words, some of us may be piling on the pounds not just because we are greedy but because we are addicted.

If Dr Thornley's claim is supported, that would open up new ways of dealing with the obesity crisis, including a food version of the nicotine patch used to help smokers quit. 

'Drug addicts have to keep taking larger amounts of their chemical of choice. They find it difficult to stop, they keep doing it despite negative consequences and they feel depressed if they do stop,' says Thornley, whose paper was published in the journal Medical Hypotheses. 'People do all those things around refined carbohydrates.'

Just how big a contribution this could be making to the obesity crisis isn't yet clear. 'We need more research,' says Thornley, 'but the evidence for refined carbs being potentially addictive is growing fast. There's a good case for treating highly refined foods as we do cigarettes - banning TV ads, taxing them and even insisting on pack health warnings.'

Studies of brain scans suggest that people who put on a lot of weight could be doing it to improve their mood; the same reason addicts take drugs.

This research shows that people with a high Body Mass Index (BMI) have fewer receptors in the part of their brains that generate pleasurable feelings. The same pattern is evident in people addicted to cocaine and alcohol.

These findings are backed by scientists at Princeton University in America, who have been turning rats into sugar addicts. The rats not only suffer cravings when sugar is taken away from them but they then binge on it when it becomes available again.

The concoction given to the rats was water with 10 per cent sugar added. Many fizzy drinks contain much more sugar than this. 'The idea that carbohydrates can be addictive is an old one but until recently it was out of favour,' says lead researcher Bonnie Spring, professor of preventative medicine at the University of Illinois, Chicago.

'Evidence has been building that high blood sugar levels affect brain circuits involved in addiction.'

A group of overweight women were offered two drinks that appeared and tasted identical, but one contained only sugary carbohydrates, such as dextrose and rice syrup, while the other had some protein added.

After they'd been made to feel depressed by thinking about something sad, most of them preferred the pure carbohydrate drink and said it cheered them up. Experiments like these are regularly used to test if a drug is addictive.

'The way these women behaved in response to the pure carbohydrate drink was similar to patterns we see in addicts,' says Spring.

Some people may be piling on the pounds because they are addicted to carbohydrates

'Addicts become tolerant of a drug so they need more of it, and we saw that with these women.'

One fascinating area of research is the link between raised blood sugar levels and the effects of smoking.

Pumping sugar rapidly into the bloodstream causes changes in various chemicals and hormones, including insulin and an amino acid called tryptophanin the brain. This creates more of the feel-good brain chemical serotonin. Nicotine also raises serotonin levels. That's why sweets can give you a temporary 'lift' if you're feeling low or irritable - as can a cigarette.

'The more instant the hit from a drug, the more likely it is to be addictive,' says Thornley. That's why giving up smoking can be so hard - the nicotine gets into your bloodstream almost instantly.

A nicotine patch helps because it provides nicotine, but more slowly. Carb addicts may benefit from getting their hit of blood sugar more slowly.

Thornley says: 'Combining refined carbs with certain foods can slow down the rate sugar gets into the bloodstream. These include vinegar or lemon juice, fat, protein and roughage. All can slow it by around half.'

So, rather surprisingly, if you have butter along with your croissant and jam, your breakfast will give you less of a sugar rush.

But while some combinations can keep blood sugar down, others can make it worse - especially caffeine in coffee.

Dr David Haslam, of the UK National Obesity Forum, agrees we must reduce the amount of refined carbohydrates we eat.

'Certainly, evidence for the idea that these foods are addictive is getting stronger,' he says, 'and anything that reduces their consumption is a good thing.'