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"Fat prejudice is the primary impediment to understanding -- or wanting to understand what obesity is all about," says a public health nurse who appears in Fat.
Physicians know too little about what causes obesity in part because, as this nurse points out, "blaming the victim has stood in the way of understanding." Here, I am reminded of how, in the past, we blamed patients suffering from depression and other forms of mental illness. For centuries, this prejudice stood in the way of understanding that mood disorders are caused by a flaw in chemistry, not character
In Fat, patients describe how even some doctors treat them with contempt: "When I went to get a Pap smear, the doctor said, ‘You're too fat; come back when you've lost weight,' " one woman recalls.
The documentary also points out that "while everyone dies ... it should perhaps come as no surprise that in our society, obese people are blamed for dying. If a thin patient comes into the hospital, has a heart attack and dies, cause of death is labeled ‘heart disease,' " says a public health nurse in the film. "If an obese patient has a heart attack and dies, cause of death is 'obesity.' "
Conventional wisdom says that if you put too much food in your mouth and don't exercise enough, you'll wind up fat. Period. As is so often the case, the conventional wisdom is wrong. Experts report that some people eat rich, fatty foods, never exercise and remain thin. Others exercise daily, diet religiously and are seriously overweight. Of course many overweight people who need to lose 20 or 25 pounds take it off and keep it off. But they are not obese -- they are not fighting a chronic condition.
Medical science has not yet sliced through the tangle of genetic, metabolic, social, psychological and environmental factors that cause obesity.
Nevertheless, scientists today have begun to look past the old-fashioned notion that obesity is merely a matter of gluttony and have made real progress in beginning to understand a terribly complicated chronic disease.
A Unique Disease -- the Body Undermines the Cure
What we do know is that "Obesity is the one disease where your body fights the cure," says Dr. Michael Rosenbaum, a Columbia University researcher working on an National Institutes of Health-funded study on weight control.
By and large, the body is programmed to help you heal. But not in this case. People think that dieting is a matter of choice, says Arthur Frank, medical director of the George Washington University Weight Management Program. But in fact, losing weight requires overcoming powerful brain signals that are working against you.
If you have ever dieted, you may already know that, once you lose some weight, your metabolism slows down and you burn fewer calories. For all your body knows, you are stranded on a desert island, starving to death. So it tries to "help." The brain is wired to eat and store fat to protect against starvation. In fact, when you lose weight, the human body has redundant systems to try to save you. That's how the human species has survived.
In "Wired to Eat," a 2005 article published in MIT Technology Review, Jeffrey Friedman, an obesity researcher at Rockefeller University, explains that the mechanism that drives us to eat is located in the hypothalamus, at the base of the brain, where two types of neurons appear to be the chief regulators of appetite. These neurons tell us when we're hungry and when we're not. The so-called NPY neuron stimulates hunger, and the POMC inhibits appetite. Each neuron is turned up or down by chemicals that wash over them. "A dominant factor in controlling weight is this basic neural circuit," says Friedman.
The chief chemical involved is leptin, a hormone produced by fat cells in the belly. When people gain weight, fat cells increase the levels of leptin, and as leptin washes over the POMC neuron, their appetite is suppressed. When people start to lose weight, body fat is reduced, which decreases the levels of leptin. Less leptin means the POMC turns down and the NPY neuron predominates, which ramps up hunger. Other chemicals -- fats, sugars and neurotransmitters -- also influence the actions of these neurons, but leptin seems to be the key.
