The Sugar-Addiction Taboo

When can you call a food addictive?
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Now that the holidays have come and gone, it’s time to look in the mirror and ask ourselves, “Did I really need to eat the whole box of chocolates?” If you did it in one sitting, you may suffer from Binge Eating Disorder, a newly-sanctioned psychiatric diagnosis in the Diagnostic and Statistical Manual-V by the American Psychiatric Association. But even if you ate the box over several sittings, you might still suffer from its more controversial cousin—Food Addiction, not yet included in the DSM-V.

There’s been a lot of heat about food addiction, but little light. None other than Nora Volkow, director of the National Institute of Drug Abuse, has spoken out in favor of the diagnosis. Yet the psychiatric and the scientific communities have been slow to get on the bandwagon. Many scientists eschew the diagnosis while others embrace it. Not surprisingly, the food industry has largely dismissed the notion. No one argues that food isn’t pleasurable, or even that food doesn’t activate the “reward center” of the brain. But can food truly be addictive? In the same way that alcohol, tobacco, and street drugs are?

Some scientists poo-poo the idea on basic principle. You don’t need alcohol, tobacco or street drugs to live, but you do need food. How can something required for life be addictive? There are three levels of motivation: liking, wanting, and needing. When we go from wanting to needing, that’s when we start to invoke the concept of addiction. As a species and as individuals, we clearly need food.  Strike one for the naysayers.

But do we need all kinds of food? Certainly, we need those foods that supply essential nutrients—those things our bodies can’t synthesize itself. These include vitamins, minerals, essential amino acids (found in protein), and essential fatty acids (found in fish and various vegetables). If you’re missing any of these you’ll get some classic nutritional deficiency disease, such as beriberi or scurvy. But what about energy? We certainly need energy, but we humans are very capable of turning protein or fats into energy when it is required. What if a foodstuff supplies only energy? Alcohol is energy, but it is certainly not required for life. There’s no biochemical reaction that requires alcohol. Thirty-nine percent of Americans are teetotalers, and while they might be missing out on some fun, they’re not exactly ill.

Which brings us to sugar. Another fun substance, full of energy, made up of two molecules linked together: glucose (kind of sweet, and not that much fun), and fructose (very sweet, and a whole lot of fun). Glucose is a nutrient, although not essential—it’s so important, that if you don’t eat it, your liver will make it. But what about fructose? Is fructose a nutrient? As it turns out, there’s no biochemical reaction that requires dietary fructose. A rare genetic disease called Hereditary Fructose Intolerance afflicts 1 in 100,000 babies, who drop their blood sugar to almost zero and have a seizure upon their first exposure to juice from a bottle at age six months. Doctors perform a liver biopsy to confirm the diagnosis. From that moment on, they’re fructose-free for the rest of their lives. And they’re among the healthiest people on the planet. Alcohol and fructose both supply energy. They’re fun—but they are not nutrients. Strike two.

But oh, do we want it. As an example, rats are not big fans of lard. But if you lace the lard with some sugar (called “cookie dough”), that’s another story — indeed, in a controversial abstract at this year’s Society for Neuroscience meeting, rats were found to prefer Oreos to cocaine. And we humans are not far behind. A recent study by Dr. Eric Stice of Oregon Health Sciences University looked at our obsession, by parsing out the fat from the sugar. Subjects laying in an MRI scanner consumed milkshakes where the fat and the sugar concentrations were dialed up or down.  Bottom line, fat stimulated the somatosensory cortex (in other words, “mouthfeel”), but only sugar stimulated the reward center. And adding fat to the sugar didn’t increase the reward any further. This study shows we want sugar way more than we want fat.

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Robert H. Lustig is a pediatric neuroendocrinologist and a professor of pediatrics at the University of California, San Francisco. He is former chairman of the obesity task force of the Lawson Wilkins Pediatric Endocrine Society and the author of Fat Chance and The Fat Chance Cookbook.

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