Sugar is a delectable enemy. Once thought to hold the secret to health, it is now believed to be fueling an obesity epidemic that encompasses 640 million people worldwide.
Despite an abundance of evidence about its dangers, Americans just can’t quit sugar. According to the U.S. Department of Agriculture, an average person in the U.S. consumes an estimated 128 pounds each year.
This seemingly infinite sweet tooth has led experts to suggest that sugar may have more control over the brain than we realize. A game-changing study published in Plos One provides some of the strongest evidence to date that they're right.
In it, researchers at Queensland University found that drugs used to treat nicotine addiction are also effective in treating sugar addiction in animals. The results not only prove a parallel between sugar and nicotine, but suggest a novel treatment for obesity.
Days before the sugar study was released, The Lancet published health data from 200 countries during the years 1975-2014. Among the study’s sobering findings: For the first time in history, more humans are overweight than underweight.
In the U.S., tied with China for the highest rates of obesity, the numbers were particularly grim. From 1975-2014, the rate of morbidly obese Americans rose from 1.3 percent to 13.3 percent. The numbers were so troubling they led the lead researcher, Majid Ezzati, to declare the epidemic at a “crisis point.”
While there are many causes of obesity, sugar has long been considered the main culprit. A study from The Lancet in 2001 found that children’s odds of obesity to increase 60 percent for every 12-ounce soda they consumed each day. Since then, numerous studies have drawn a connection between the two.
Most recently, one published this March by researchers from the University of Reading, the University of Cambridge, and Arizona State University, found that—out of a group of more than 1700—those who consumed the most sugar were 54 percent more likely to be obese.
Despite the public health attack on sugar for its connections to obesity, the leader of the groundbreaking Plos One study was not searching for an end to this problem. In fact, Dr. Selena Bartlett wasn’t studying sugar at all. A neuroscientist based at the University of California, San Francisco, Bartlett was studying alcohol’s effects on the brain when she stumbled on sugar.
Initially using sugar as a control, she was shocked to realize that it performed the same mechanism on the brain. “Sugar and alcohol affect the brain in the same way—the brain region that underlies addiction,” she tells me. Both elevate dopamine levels in the same reward pathway, which in turn drives our motivation to keep consuming.
Shortly after connecting alcohol and sugar’s effect on the brain, a colleague who’d been studying nicotine’s effect on the brain, saw the scans. Much to Bartlett’s surprise, the nicotine brain scans mirrored those of alcohol and sugar as well. “We realized they were all driving changes in the the exact same pathway of the brain,” she says. “We were aghast.”
Bartlett says the discovery that the brain responded to sugar the same way it did to nicotine, one of the most addictive drugs in the world, was both surprising and logical.
“From a neuroscience perspective it makes total sense to me because nicotine is one of the most addictive things on the planet, it binds to very specific receptors,” she says. “And to think that sugar is activating the exact same pathway that nicotine does, it makes so much sense why it’s so addictive.”
Her goal wasn’t so much to find a solution to sugar addiction as to prove that it acts like nicotine, and is just as dangerous. To do this, she took the equation and flipped it on its head. If sugar activates the same pathway as nicotine, then drugs used to treat nicotine addiction would also treat sugar addiction. Right?
Following in her colleague’s footsteps, Bartlett used the popular FDA-approved drug Chantix, a smoking cessation drug whose technical name is varenicline. Created by Pfizer, varenicline is a nicotine agonist, meaning it does not contain the actual drug. Instead, it works by activating the nicotine receptors in the brain—the same receptors, Bartlett found, that sugar activates.
When Bartlett administered the drug to rats who had only been consuming sugar for a short period of time, it had no effect. But in those who had been consuming a large amount of sugar long-term, whose receptors had been permanently altered, it “significantly reduced” sugar consumption.
“Excess sugar consumption has been proven to contribute directly to weight gain. It has also been shown to repeatedly elevate dopamine levels which control the brain’s reward and pleasure [centers] in a way that is similar to many drugs of abuse including tobacco, cocaine and morphine,” Bartlett said in a press release. “After long-term consumption, this leads to the opposite, a reduction in dopamine levels. This leads to higher consumption of sugar to get the same level of reward.”
Since nicotine and sugar wear down the same receptors, they both respond to the same drug. The results not only highlight varenicline’s ability to curb sugar cravings, but suggest that these drugs could prove a novel new treatment for the obesity epidemic in the future. That’s not to say, however, that those who can’t get enough sugar should rush to the pharmacy.
“We don’t want people going to the doctor and asking for it,” says Bartlett. Until clinical studies on humans have been done, she says it’s unsafe. “I don’t like to push drugs on people because they’re already on a lot of drugs,” she says. Taking Chantix comes with risks—which may, for someone not addicted to nicotine, outweigh the benefits. “Further studies are required but our results do suggest that current FDA-approved drugs [to treat nicotine addiction] may represent a novel new treatment strategy to tackle the obesity epidemic.”
While Bartlett seems hopeful that the evidence will underscore how serious our attachment to sugar is, she’s careful to clarify that our relationship to sugar is complicated. Not all sugar is bad, and removing it entirely isn’t something she advocates.
“I really believe in everything in moderation,” she says. “Eating a small amount of sugar is not going to kill you or make you addicted to it. People get extreme and eliminate it from their diets but you don’t need to do that. It’s about not having that big doughnut everyday, or skipping that soda.”