SWEET TALK

We're tlod we can get hooked on sugar like drugs or alcohol. But is it solid science or irrelevant hyperbole ?

Like sitting and cigarettes, sugar is a familiar enemy. We’ve made friends with healthy fats and are back on speaking terms with carbs. But the sweet stuff? It’s impossible to enjoy a piece of cake or even a glass of orange juice without a saccharine-laced twinge of guilt. Yet according to the report Sugar Consumption In Australia: A Statistical Update, we’re still consuming nearly five times more sugar than the six teaspoons per day recommended by the World Health Organization. They say knowledge is power, so why is sugar more powerful?

We’ve recently seen the public narrative take a new twist. Sugar is no longer simply unhealthy; increasingly, it’s called “addictive” – and not just in a dramatic, “OMG, I can’t stop at one Tim Tam!” sort of way. Some scientists believe sugar invites compulsive consumption the way drugs and alcohol do.

Two researchers published a study in Nature Neuroscience in which they tested what happened when rats binged on a stoner’s fantasy menu: cheesecake, pound cake, frosting, chocolate, sausage and bacon. Not surprisingly, the rats that had extended access to the junk food ate almost twice as many kilojoules as the control rats and quickly gained weight. But here’s where it gets interesting: the control rats and the newly fat rats were then both allowed to eat the junk food, but this time around, their feet were shocked. The rats that had little or no prior access to the junk food backed away from the meal, but the fatties who’d already been exposed kept right on eating through the pain. Finally, when the animals were put back on their regular diet, they went on a two-week

hunger strike, voluntarily starving themselves, in essence, rather than returning to “healthy” food.

Although the rats enjoyed the processed meats, they didn’t go as crazy eating them as they did with the cheesecake, suggesting that Kitkat fans shouldn’t be lumped with bacon-wrapped chorizo lovers. While fat can also spur a release of dopamine (the pleasure hormone), it affects the brain’s satiety signals differently to sugar, says Dr Nicole Avena, a neuroscientist and co-author of Why Diets Fail (Because You’re Addicted to Sugar). “You can’t really binge on greasy hamburgers because you get full from them quickly, but we don’t see that happening with sugary, high-carb foods,” she explains. “It could take half an hour to feel full, and by then you’ve already eaten half a box of biscuits.”

In fact, a study published last year in the journal Eating Behaviors examined the differences among 283 people, some who primarily craved sweets and other high-carb foods, and others who generally preferred fatty foods. The sugar fiends were more likely to binge, but the fat fans had higher BMIS. “Sugar and fat may both be problematic, but through different mechanisms,” says the study’s author Michelle Joyner. “But foods high in fat and sugar, like chocolate cake, might be particularly risky because fat makes food taste better, so it’s more likely to be overeaten. Plus, the high sugar content could make one likelier to consume it in an addictive way.”

But sceptics chafe at the idea that we can become addicted to something necessary to live. We’re wired to desire sweet substances, says Dr Caroline Davis, a psychology professor at Canada’s York University. Sugar is converted quickly into glucose, a form of energy necessary for the functioning of the brain and nervous system, and was adaptive for survival – during our huntingand-gathering days, sweetness was a sign food was safe. “Things that were toxic tasted bitter,” she says.

Perhaps the largest issue for naysayers is: where’s the evidence among creatures other than lab rodents? While compelling brain imagery shows overactive reward circuits in obese people or those resistant to the satiety hormone leptin, the results are inconsistent in the general population, says Dr Kent Berridge, a professor of psychology and neuroscience at the University of Michigan in the US. “The big question is whether it’s a few people who are showing these brain overreactions, or whether nearly all of us have the capacity to be addicted to our most tempting favourite foods,” he says.

Still, despite what you learned in high school, not all people who try drugs or alcohol develop dependencies. The next direction for research is delineating why some of us are more sugar-sensitive than others. In the meantime, if you’re someone who just has to finish the tub of ice-cream, perhaps the addiction analogy might help you cut back. Or at least polish it off standing up – sitting only adds insult to injury.

“You can’t really binge on burgers because you get full from them quickly, but with sugary, high-carb foods, it could take half an hour to feel full, and by then you’ve eaten half a box of biscuits”