Eating to Live or Living to Eat?
Picture a big, moist, scrumptious chocolate cake layered in frosting and dazzled with sprinkles. Imagine the bliss of biting into that luscious chunk of chocolate goodness. Now, what do you notice? How are you feeling?
Well, an interesting article from the Wall Street Journal on July 13, 2010 explored differences in brain chemistry among obese and non-obese people when it comes to dessert. In her article, “Eating to Live or Living to Eat”, Melinda Beck writes that normal-weight people eat according to their ‘homeostatic system’. In other words, they are eating for survival. Obese individuals, on the other hand, tend to eat according to the ‘hedonic system’, meaning that they are eating for pleasure. When the ‘homeostatic system’ is working correctly, chemical messengers are sent to the brain once food reaches the stomach and intestines, signaling the brain to stop eating. Hence, that chocolate cake for dessert isn’t as tempting. However, when the ‘hedonic system’ has taken over, seeing, smelling, and even hearing the word “cake” activates areas of the brain involved in reward, emotion, memory and thinking. This triggers the release of dopamine, the brain’s “pleasure chemical”. Brain scans show that obese people chemically have stronger reactions to food than non-obese people.
Studies show that images of high-sugar and high-fat foods shown to obese people trigger a strong response in the ventral tegmental area (VTA), a tiny spot in the midbrain where dopamine, the “pleasure chemical” is released. According to Susan Carnell, a research psychiatrist at the New York Obesity Center at Columbia University, “when obese people see high-calorie foods, a widespread network of brain areas involved in reward, attention, emotion, planning, memory and motor plannning is activated, and all the areas talk to each other, making it hard for them to resist”.
The article goes on to explain that overweight people have strong reactions to food in the amygdala -the emotional center of the brain, while healthy-weight individuals show an amygdala response only when they are hungry. It just so happens that food activates the exact same areas of the brain for over-eaters as do drugs for drug-addicts. The point is that obesity is not simply a matter of laziness or self-control. It is an actual chemical and physiological condition. It’s like asking a poised and ready Olympic sprinter not to lunge when the gun is shot.
The question is, of course, which came first? Does persistent overeating cause the brain to stop responding to leptin and the body’s built-in fullness signals? Or does a chemical imbalance cause overeating? While I am certainly no expert on psycho-physiology or brain neurology, my work thus far in the field of eating disorders has pointed me to emotional roots of behavior every time. Without exception, disordered eating has pointed to some deficit in relationship, connectedness, or intimacy.
A peruse through my old Biological Psychology book also reminds me that the amygdala is greatly responsible for primal emotions such as fear, anger, etc. In other words, this part of the brain influences reactions that are instinctual. They are not controlled by the rational part of the brain. The amygdala also responds to emotional stimuli that people cannot identify consciously. I have heard many over-eaters tell me that they eat without even being conscious of it. It’s like they need that piece of cake for survival and they don’t know why. It’s as if they are under a spell. Could they be responding to this unconscious survival instinct? We also have survival instincts for love and connectedness, which light up the same areas of the brain. Could food be the brain’s unconscious attempt at meeting these relational survival needs?
Comments