I'm sitting in a comfortable chair, in a tastefully lit, cheerfully decorated drug den, watching a steady line of people approach their dealer. After scoring, they shuffle off to their tables to quietly indulge in what for some could become (if it hasn't already) an addiction that screws up their lives. It's likely you have friends and family members who are suffering from this dependence—and you may be on the same path yourself. But this addiction is not usually apparent to the casual observer. It has no use for the drama and the carnage you associate with cocaine and alcohol. It's slower to show its hand, more socially acceptable—and way more insidious.
     I'm in a Panera Bread outlet. The company is on Fortune's 2010 list of the 100 Fastest Growing Companies and earned more than $1.3 billion in 2009, mainly from selling flour and sugar by the railcar. Last year, Zagat named it the most popular large chain in the United States and ranked it second in the Healthy Options category. The company responded by touting its "wholesome" food. Sure, Panera sells a few salads. But why do the scones, pastries, baguettes, and bear claws get all the good lighting? Why are the grab-and-go packs of cookies and brownies next to the register? What need is fulfilled by serving soup bowls made of bread, with a mound of bread for dipping, and then offering more bread on the side? How come it's noon and the couple behind me are eating bagels while the guy to my right is sawing into a cinnamon roll with a fork and a knife like it's a steak?
     The answer is that fast-burning carbohydrates—just like cocaine—give you a rush. As with blow, this rush can lead to cravings in your brain and intrusive thoughts when you go too long without a fix. But unlike cocaine, this stuff does more than rewire your neurological system. It will short-circuit your body. Your metabolism normally stockpiles energy so you can use it as fuel later. A diet flush with carbohydrates will reprogram your metabolism, locking your food away as unburnable fat. When you get hungry again you won't crave anything but more of the same food that started you down the path to dependency. Think of this stuff as more than a drug—it's like a metabolic parasite, taking over your body and feeding itself.                    
     You aren't supposed to talk this way about carbohydrates. According to USDA dietary recommendations, they are not only healthy but are supposed to make up the majority of the food we eat—45 to 65 percent of all calories. Carbs, which are classified as starches and sugars, make up the essence of bread, cereal, corn, potatoes, cookies, pasta, fruit, juice, candy, beer, and sweetened drinks—basically anything that isn't protein or fat. Our government's recommendations were established in the 1970s and have since been accompanied by an explosion of obesity and diabetes. The advice came about as early nutrition scientists rallied around a misguided maxim that remains embedded in the fabric of our attitudes toward food to this day: Eating too much fat makes you fat. But science never bore out this pre-Galilean view of nutrition. What is now clear is this: At the center of the obesity universe lie carbohydrates, not fat.
     "You could live your whole life and never eat a single carbohydrate—other than what you get from mother's milk and the tiny amount that comes naturally in meat—and probably be just fine," says Gary Taubes, the award-winning author of Good Calories, Bad Calories, which is helping to reshape the conversation about what makes the American diet so fattening.
     If all you knew about food is what you read in the USDA guidelines, you'd think our bodies conveniently come into the world seeking the one nutrient that is cheap and amenable to commercial mass production: carbohydrates. "Sugars and starches provide energy to the body in the form of glucose, which is the only source of energy for red blood cells and is the preferred energy source for the brain," says the latest edition of the guidelines. Wrong, says Taubes, who just released Why We Get Fat, a layman's version of his influential scientific tome. In the absence of carbs, your body will burn fatty acids for energy. It's how you sleep through the night without eating for eight hours. "The brain does indeed need carbohydrates for fuel," Taubes says, "but the body is perfectly happy to make those out of protein, leafy green vegetables, and the animal fat you're burning." As a pair of Harvard doctors (one an endocrinologist and one an epidemiologist) wrote in the Journal of the American Medical Association last summer, carbohydrates are "a nutrient for which humans have no absolute requirement."

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The Diets That Work

     You wouldn't know it from reading the latest dietary headlines, but all of the popular diets—from Atkins to Dean Ornish (Bill Clinton's weight-loss plan) to the diet-of-the-moment, Paleo—are successful because the most important change they advise is the same: stop eating refined carbohydrates. This only reminds us of what had been the conventional wisdom in medicine for hundreds of years before the USDA stepped in: that sugar, flour, potatoes, and rice are what make a person fat, not meat and milk.
     Forty years into the low-fat, high-carbohydrate way of eating—we can thank it for "diabesity," shorthand for the societal prevalence of type II diabetes paired with obesity—it seems clearer than ever that our problem lies not simply in carbohydrates, but in their fundamental addictiveness. They sidestep our defenses against overeating, activate brain pathways for pleasure, and make us simultaneously fat and malnourished. They keep us coming back for more, even as they induce physical decline and social rejection. They achieve this more effectively than the controlled substances that can get a guy thrown into jail. Maybe the question isn't whether carbohydrates are addictive, but whether they are the most addictive substance of all.
     In 2007, researchers at the University of Bordeaux, France, reported that when rats were allowed to choose between a calorie-free sweetener and intravenous cocaine, 94 percent preferred the sugar substitute. The researchers concluded that "intense sweetness can surpass cocaine reward. . . . The supranormal stimulation of these receptors by sugar-rich diets, such as those now widely available in modern societies, would generate a supranormal reward signal in the brain, with the potential to override self-control mechanisms and thus to lead to addiction." Nicole Avena, an expert in behavioral neuroscience at the University of Florida in Gainesville, has spent many hours analyzing the behavior of rats enticed into sucking up sugar. She says that feeding on sugar can, like snorting coke, lead to bingeing, withdrawal, and craving. It does this by lighting up the same circuitry within the brain triggered by cocaine and amphetamines, the dopamine center.
     But a carbohydrate addiction is potentially more destructive than an 8-ball-a-day habit, because it hijacks your metabolism. If you eat a low-carb diet, you are able to remain satiated between meals, because the body will burn its fat stores. But eating carbs, especially refined varieties like sugar or flour, sweetened drinks, or starches, causes the body to release the hormone insulin. The body secretes insulin as a response to high blood sugar—a serious, even potentially lethal health risk over time. The hormone directs cells to extract sugar from the blood and store it as fat, and what's worse, in order to get sugar out of the blood as efficiently as possible, insulin makes it extremely difficult for the body to burn its fat stores. Over time, the presence of insulin in our carb-heavy diet causes diminishing returns. As our cells become resistant to the effects of insulin, our bodies frequently release even more of it to compensate. The result is a blood-sugar vacuum: The body craves more of what the hormone feeds on and triggers our hunger mechanism, which works subconsciously, to direct us toward the nutrient causing all the problems in the first place—carbohydrates. You get fatter and your body craves even more carbs in order to maintain your increasing weight. Drug cartels can only dream of a narcotic with an addiction cycle this powerful.
     Once hooked, can you quit your carb addiction? It's not like there's a carb-cessation program at Promises, after all. Taubes says it won't be easy, but given the alternatives, you simply have to try. And cold turkey is as good a method as any. "Anecdotal evidence suggests that the craving for carbs will go away after a while," he says, "although whether a while is a few weeks or a few years is hard to say." And frighteningly like an addict in recovery, you're unlikely ever to be totally cured, and you'll always be tempted to relapse when the opportunity arises. Be warned: The number of Panera Bread outlets is 1,421 and counting.

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How You Get Hooked (Over Time)

1. When you take in carbs, like Gatorade or whole-wheat bread, you secrete the hormone insulin. Even thinking about carbs causes this to happen.
2. Refined carbs spike blood sugar, and this is a big problem. The first result is that your body immediately stops burning its existing fat stores.
3. Too much blood sugar is a dangerous situation, and in response, insulin, a hormone, rips it from your blood and tells the body to store the energy as fat (in men this first happens around the waist).
4. Normally your liver controls blood sugar, but because you eat so many carbs you have a constant supply of insulin circulating. This turns out to be bad—very bad. This causes you to become resistant to insulin.
5. Insulin resistance means your body pumps out more insulin to make up for the deficit. Now you're getting fat, but what's worse is that your body desires even more carbs as fodder for the excess insulin.
6. You get fatter and fatter and your body craves more carbs to feed your increasing girth. This destructive cycle is why Americans are so overweight (the process doesn't happen overnight).