Fat Chance: The bitter truth about sugar. Dr. Lustig Robert

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СКАЧАТЬ Needing

      Look, we all like fast food. And why wouldn’t we? It’s designed to contain the greatest concentration of fat, sugar, salt, and caffeine, and is placed into as small a package as possible. Yummmm. It provides food cheaply, quickly, and without table service. The pretty packaging and restaurant environment increase its salience (the properties that make you like it more). Ten years ago, fast food locations in the United States generated more than $125 billion, which accounts for 15 percent of sales of the entire U.S. food industry. But liking it isn’t the same as wanting it. And wanting it isn’t the same as needing it.⁶

      Liking is an aesthetic state. You can turn it on and turn it off. As dopamine is released into the NA, our consumption of a Big Mac heightens our sense of reward. Then comes the insulin rush, and that should be the end of it. But when you’re insulin resistant, wanting is a psychological state and needing becomes a physiologic state. You can’t turn it on and off anymore. This is the nature of addiction to any substance of abuse. It’s what happens with nicotine, morphine, cocaine, and alcohol—and it happens with food. It can happen to anyone. It can happen to you.

      Substance dependence, in this case synonymous with addiction, is defined by the American Psychiatric Association (APA) as “a maladaptive pattern of substance abuse leading to clinically significant impairment or distress.” There is currently no standardized definition for food addiction despite many hypotheses in the medical literature. There are seven criteria for substance dependence according to the APA Diagnostic and Statistical Manual, the DSM-IV-TR. The first two are considered physiologic, whereas criteria 3–7 are considered psychological dependence. All these are seen in the obese, especially those who frequent fast food restaurants. To be considered addicted to any substance of abuse, one must meet at least three of the seven.

      1. Tolerance. This is defined as the need for more substance to get the same effect, or when the same amount of substance produces less effect with continued use. That Big Mac still generates the dopamine rush, but the reward isn’t maintained, as your insulin won’t clear the dopamine from the NA. Since insulin resistance generates leptin resistance, you can’t stop the dopamine neurons in the VTA from firing in the first place. So your NA is awash in dopamine, and the insulin rush from the meal can’t turn it off. Since your hypothalamus and your NA won’t respond to the leptin signal, the drive to eat just keeps coming. And here’s the kicker: the more and the longer your NA is exposed to dopamine, the more those D₂ receptors are going to be down-regulated. After chronic dopamine exposure, the D₂ receptors themselves start to disappear. The locks vanish, much to the chagrin of the keys, which have nowhere to go. Now it takes more dopamine to ensure that the few receptors that don’t disappear are occupied. You need to eat more Big Macs just to get the same level of reward.

      2. Withdrawal. This is characterized by physical signs (such as tremors) and psychological ones (anxiety, depression). This occurs due to lack of dopamine D₂ receptor occupancy. In animals, anxiety and depression are indicated by unwillingness to spend time in a risky environment. In humans, withdrawal is expressed as symptoms of depression and anxiety. If you try to stop eating those Big Macs, your dopamine drops and you are consumed by feelings of anxiety and depression (just like those patients treated with rimonabant—the “anti-munchie” medicine). The only choice is to increase the dopamine, reoccupy those diminished D₂ receptors, and maintain the vicious cycle of Big Mac consumption.

      If you need proof, I suggest you rent the 2004 documentary Super Size Me. The film’s author and star, Morgan Spurlock, began as a reasonably healthy specimen at 6 feet 2 inches and 185 pounds (for a BMI of 23.8, within the normal range). He was eating a reasonably healthy diet (his girlfriend was a vegan chef) before beginning a thirty-day ordeal of eating every meal at McDonald’s. By day eighteen, he relates to the camera, “You know, I was feeling awful. I was feeling like s--t. I was feeling sick, and unhappy…. Started eating; now I feel great. I feel so great, it’s crazy.” Mr. Spurlock just described withdrawal. In eighteen days, he went from being a person with healthy eating habits to a fast food addict.

      3. Bingeing. This is defined as an escalation of intake, using a greater amount of the substance or using for a longer duration than intended. In animals, this can be measured by an increase in the number of times the animal presses a lever to self-administer a drug—or, in the case of a human, continuing to eat after satiety has been achieved. One can easily conceptualize binge drinking (think of the movie Animal House or your stereotypical chug-a-lug frat guy), but binge eating is harder to define. It is highly subjective, since what is a large amount to some may not be perceived as unusual by others. Binge eating disorder includes eating until uncomfortable; eating when not hungry; eating alone due to shame; feeling disgusted, depressed, or guilty after overeating; and marked distress over the bingeing. Many afflicted people will consume massive amounts of food, such as an entire sheet cake, alone and in the dark of their kitchen, with massive shame.

      4. Desire or attempts to cut down or quit. As mentioned previously, diets and miracle drugs generate over $160 billion annually. Those who are overweight or obese are almost always on some new diet kick and are frequently “weight cycling,” or yo-yoing. Juicing, cleansing, meat only, carbs only—they grasp for any possible solution. And it’s almost never sustainable. After a period of days, weeks, or months, they frequently binge on the substance from which they were abstaining (often sugar), and the weight is gained back. The sense of failure and ensuing depression can be overwhelming. The obese then read a new article or book about the latest craze and begin the cycle again ad infinitum. It’s not that they aren’t trying. Their lives are often consumed by these attempts.

      5. Craving or seeking. This is described as an intense drive to self-administer drugs. In food addiction research, craving is illustrated by the motivation to seek food. Drug craving and seeking have been experimentally described as a form of learning, where dopamine signaling facilitates the consolidation of memory; past experiences are used to inform future decisions. Rats “press the lever” for drugs because they have learned that it is rewarding. We press the credit card button for Frappuccinos.™

      6. Interference with life. This is defined by important work, social, or other life activities being compromised. Obesity can significantly hamper an individual’s quality of life. Mobility is markedly more difficult. Airlines may refuse you passage if you don’t fit into the seat. Employers may refuse to hire you based on your weight. Diabetes can lead to limb amputation, requiring use of a wheelchair. During the thirty days of Spurlock’s Super Size Me adventure, he gained 24.5 pounds, experienced mood swings, sexual dysfunction, and fat accumulation in his liver. While his experience of eating every meal at McDonald’s may be deemed extreme, these physical and physiological effects occurred within only a thirty-day period.

      7. Use despite negative consequences. This is defined as continued use despite knowledge that use will make the problems worse. The health consequences associated with obesity are numerous (see chapter 19). Despite knowing and experiencing these health problems, the eating pattern continues unabated.

       What Makes Fast Food Addictive?

      In humans, food addiction is often compared to established criteria for substance dependence.⁷ One problem with this approach is that it shifts focus away from the potentially addictive properties of the food and onto the individual “afflicted” with the addiction. We prefer to focus on the addictive potential of the food itself by placing it in the scope of other identified substances of abuse. Alcohol is the most analogous substance to fast food for several reasons, including its biochemistry (see chapters 11 and 22).

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