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

weight. She stated that the surgery had removed her hunger. So how and why did she gain it all back? It turns out she switched schools in sixth grade. The kids in the new school hurled insults, calling her Fatso, Miss Piggy, and The Blob. Despite a lack of hunger, the stress of her new situation caused her to eat incessantly. Janie switched to a new middle school, where she got along better with her peers, and lost weight again.

      This poor young lady is triply cursed. First she gets a brain tumor. Then she gets obese as a complication of the brain tumor. To top it all off, she has the misfortune of being a teenager (possibly the worst of the three). Even though we did our best to treat this girl’s biochemical difficulty, the social difficulty turned out to be even more potent.

      I take care of kids for a living. While the majority of them are cute and adorable, some kids can be downright mean. Especially adolescents. Bad behavior is de rigueur nowadays. How many movies out of Hollywood play on this adage? Rent Mean Girls, Sixteen Candles, or Can’t Buy Me Love in case you’ve forgotten what high school is like. Maybe it’s the testosterone and estrogen of puberty that makes some teenagers angry and turns them into bullies. Perhaps they build themselves up by taking other kids down with degrading remarks and slurs. Maybe it’s their upbringing. They see how their parents handle social issues and they emulate them. (Beware the mothers of the PTA in the San Fernando Valley.) But I do know one thing: many kids (and adults) respond to psychological stress by eating.

      Coincident with the rise in obesity throughout our society is an increased prevalence and severity of psychological stress.¹ Two mechanisms by which stress leads to obesity are stress-induced eating and stress-induced fat deposition.² Both animals and humans have been documented to increase their food intake following stress or negative emotion, even if the organism is not hungry. Further, the type of food eaten tends to be high in sugar, fat, or both. There’s a load of evidence that humans are more stressed today than we were thirty years ago, which correlates directly with the expansion of our waistlines.

       Cortisol: Can’t Live with It, Can’t Live Without It

      The relationship between stress, obesity, and metabolic disease begins with the hormone cortisol, which is released by your adrenal glands (located on top of your kidneys). This is perhaps the most important hormone in your body. Too little cortisol, and you can die. If you’re missing any other hormone in your body—growth, thyroid, sex, or water-retaining hormones—you’ll feel lousy and your life will be miserable, but you won’t perish. But if you’re missing cortisol, you can’t handle any form of physical stress. As David Williams stated in the 2008 PBS series Unnatural Causes, “Stress helps to motivate us. In our society today everybody experiences stress. The person who has no stress is a person who is dead.” The acute rise in cortisol keeps you from going into shock when you dehydrate, improves memory and immune function, reduces inflammation, and increases vigilance. Normally cortisol will peak in a stressful situation (when you’re being chased by a lion or your boss is yelling at you for not getting the memo). Cortisol is necessary, in small doses and in short bursts.

      Conversely, long-term exposure to large doses of cortisol will also kill you—it’ll just take longer. If pressures (social, familial, cultural, etc.) are relentless, the stress responses remain activated for months or even years. When cortisol floods the bloodstream, it raises blood pressure; increases the blood glucose level, which can precipitate diabetes; and increases the heart rate. Human research shows that cortisol specifically increases caloric intake of “comfort foods” (e.g., chocolate cake).³ And cortisol doesn’t cause just any old weight gain. It specifically increases the visceral fat (see chapter 8), which is the fat depot associated with cardiovascular disease and metabolic syndrome.

      Beginning in the 1970s and lasting more than thirty years, the seminal “Whitehall study” charted the health of twenty-nine thousand British civil servants.⁴ In the beginning, the scientists hypothesized that the high-power executives would have the highest rates of heart attack and coronary disease. The opposite proved to be true. Those lowest on the totem pole exhibited the highest levels of cortisol and of chronic disease. This held true not just on the bottom rung: the second person down on the social ladder had a higher likelihood of developing diseases than the person on the top rung, the third had a higher predisposition than the second, and so on. Death rates and illness correlate with low social status, even after controlling for behavior (e.g., smoking).

      The same holds true in America. The prevalence of diseases such as diabetes, stroke, and heart disease are highest among those who suffer from the most stress, namely middle- and lower-class Americans. These stressors are acutely felt in children as well. Almost 20 percent of American children live in poverty. The lifelong consequences of food and housing insecurity are toxic to the brain and alter its architecture early in life.⁵ In particular, cortisol kills neurons that play a role in the inhibition of food intake.⁶ Whether one builds a strong or weak foundation in childhood is a great determinant of later health and eating patterns. Thus, childhood stress increases the risk of obesity during adolescence and adulthood.

      Some of the factors associated with lower thresholds for stress and higher “cortisol reactivity” are low socioeconomic status, job stress, being female, scoring high in dietary restraint (a measure of chronic dieting), and an overall lack of power and confidence. Taking three buses to get anywhere, working two or more jobs, figuring out how to put food on the table, and not knowing whether you will be able to pay the rent—all significantly affect not just your state of mind but also your physiological state. And if you are not Caucasian, the stresses associated with racism will double these health effects. African Americans and Latinos suffer from higher mortality rates of nearly every disease than their white counterparts. While there are certainly genetic influences, stress plays a major role in health disparities among the races.

       The Science of Stress

      The stress response is a cascade of adaptive responses that originate in the central nervous system. When an individual perceives stress (anything from a plane crash to a calculus test), the body interprets and processes the threat in an area of the brain called the amygdala. From there, the amygdala switches on two other systems. First, like a game of telephone, the amygdala tells the hypothalamus, which tells the pituitary, which tells the adrenal gland to release cortisol. In an acute situation, cortisol feeds back on the hypothalamus to stop further secretion, and its effects would be short term and limited. (I escaped the lion! Ah, sweet relief. Time for a nap