IN MEDICAL TERMS, obesity is defined simply as an excess amount of adipose or fat tissue. The terms adipose and obesity both have their origins in Latin. Adipose stems from adeps, meaning fat, while obesity comes from the Latin—obesus—which, in turn, is a contraction of two Latin words, ob and edere, meaning to devour or eat away. At the most basic level, obesity is a disease of imbalance. Energy (in the form of calories) that is coming into the body outweighs the energy that is expended.

Historically, the disease has been known in every society, and can be evidenced as far back as the Ancient Egyptians. Hippocrates, the so called father of medicine, made one of the first accounts of the risks posed by being obese, and his suggestions for treatment were not that far removed from diets of today. He prescribed hard labor, sleeping on a hard bed, eating only once per day, eating fatty food for greater satiation, and walking naked as long as possible! Certainly, his patients would have lost weight when following that regimen, however, the practicality of implementing that medical advice today is questionable. The critical issue, however, is why obesity, despite origins in the ancient world, a simple cause and treatment, is one of the most salient threats to the welfare of our present society.

In recent years, the public's general interest and alarm in the obesity epidemic has become apparent. It is no longer possible to avoid the issue: newspapers, the evening news, health magazines, the fashion industry, television and movies, all contribute to the public's both interest, and inevitable saturation from the issues surrounding this epidemic. Cultural analysts would not be far off in stating that our current society is obsessed with both food, and the consequences of an excess of food—obesity. For a society that relies on the mass media for much of its education, the genuine fear of many health and medical professionals is that the general public will receive incorrect messages. As someone who works in the field, I often find myself biting my tongue at family functions or social gatherings, simply to prevent getting involved in arguments about the latest diet fads (most of which are ineffective). However, I also understand the public's deep frustrations over the state of medically purveyed obesity treatments—because there is no magic pill or treatment to cure and eradicate the disease. The best medical advice is to reduce your caloric intake by eating a variety of healthy foods and increase the amount of physical activity you get. Seems quite simple, but still, the majority of us will struggle to maintain a healthy weight, and this struggle is one we must fight for the rest of our lives.

The current interest and obsession with both food and obesity in present society is a predictable reaction to the recent increases in the occurrence of this disease. Over the past three to four decades, the prevalence of obesity in the United States has been consistently [Page viii]on the rise, and depending on what resource you consult, the number of obese adults is estimated at anywhere between 30 and 35 percent. If you expand this definition to include overweight (a less severe condition of excess body weight), those numbers skyrocket to between 60 and 65 percent. Further, according to most recent data from the National Health and Nutrition Examination Survey (NHANES), one of the primary surveys designed to study the health and nutrition status of adults and children in the United States, it is estimated that between 16 to 18 percent of children and adolescents are obese, while over one-third are overweight. Clearly, it is no wonder why some experts have suggested that researchers no longer ask the question “What causes people to become obese?” and that a better question might be, “How do some people remain lean in an environment of excess?”

The cut-offs for obesity are defined using reference standards for Body Mass Index, or BMI. BMI is a unit of weight that is adjusted for height, and is thought to be a good estimation of the amount of body fat one has. Depending on where BMI lies, cut-offs for lean, overweight, and obese have been defined. These classifications were set by expert committees who assessed some increased risk of morbidity and mortality with increasing BMI. But these categories are not without controversy, and even the scientific research community is at odds for defining the exact contribution that excess weight makes toward reducing life expectancies. The fact that obesity lowers quality of life is less controversial though, and it is well documented that even losing modest amounts of weight can improve health parameters and improve overall well-being.

While the contribution of obesity to increasing mortality risk in adults can be debated, there is growing concern that today's youths will be the ones to pay most dearly for this epidemic. If estimates continue as projected, the current generation of children will grow up to become the most obese in history. More importantly, it is expected that today's youths will actually be the first to have shorter life expectancies than their parents, a fact mainly attributed to early deaths due to obesity-related diseases. A clear example of this can be seen with Type 2 diabetes, the type of diabetes that results because the body can no longer produce enough insulin to meet the body's needs. Obesity exacerbates the progression of this illness, and over the course of 10 to 20 years, eventually the body becomes completely resistant to the effects of insulin. Until recently, this disease was rarely seen in children. Juvenile onset diabetes, now called Type 1 diabetes, was the form of this disease seen in children. Currently, it is estimated that over half of new diabetes cases in children are now Type 2. Once known as “adult-onset diabetes”, Type 2 diabetes can now be seen in children as young as 2 years of age. The combination of the right genetic and environmental conditions has made for astoundingly rapid increases in the development of this disease in a population where it was once nonexistent.

The statistics are undoubtedly alarming. While awareness of the problem is arguably at an all time high, the general public and most health professionals are still unaware as to how to treat obesity, both on an individual basis and at the level of public policy. Furthermore, the perception amongst both the lay public and many health professionals is that obesity is largely due to a lack of will power and occurs in individuals of weak constitution. Thus, we blame the obese individual for his or her condition. Persons who suffer from the illness are made to pay for two seats on an airplane. They are rejected for health and life insurance policies. They are stigmatized in the mass media, in the workplace, and even by the medical professionals who treat them. Rarely has a medical condition been encountered where such ambiguity exists over how to treat the illness, and where on many occasions, the burden and blame is put on the individual. Therefore, the most important reason for this text is to provide education and awareness to the public that obesity is a complex, multi-faceted disease with biological, environmental, and socially mediated causes and consequences.

While several experts in the field recently debated the relationship between obesity and increased mortality, there is little argument for the direct role that being overweight plays on reducing quality of life. The burdens due to obesity, both individually and on a population level, are many. During childhood, obesity is particularly debilitating, and these children are often teased relentlessly and bullied by their classmates. Obesity is also associated with a range of health problems, such as Type 2 diabetes, cardiovascular disease, certain cancers, osteoarthritis, sleep apnea, hypertension, and many others. Thus, shorter life expectancies in obese patients are most likely attributed to the wide range of afflictions that coincide with this condition. Even if life expectancy is not shortened, the quality of those years for an obese individual might be lower, as they are prone to suffer both physically [Page ix]and cognitively. As a society, we all pay this burden through higher health care costs, which in 2005 were estimated at $75 billion annually. The cost to treat both obesity and obesity related illnesses contributes to nearly 10 percent of the total medical expenditure in the United States.

One of the most important questions to ask is why we, as a society, continue to “expand,” and similarly on an individual level, why is it so difficult to maintain a healthy weight. This question will be the focus of many of the topics explored in this encyclopedia. The answer is complex, in that despite the fact that obesity is simply a disease of energy imbalance, the exact reasons for this imbalance are vast, and in some cases unknown. Variations in biology between one human and another have blessed some with a perpetually lean frame, while others continually battle to keep their waist lines down.

Currently, we know of nearly 250 genes that can be altered, with outcomes affecting body weight regulation, and thus risk for obesity. Perhaps more pervading, though, is the current environment in developed countries that seems to encourage energy consumption. There are few places in the world where one can travel and not be within quick access to multiple fast restaurants and convenience stores. Economic conditions are such that high fat, high carbohydrate foods cost much less per calorie than do more healthful fruits and vegetables. To complicate matters, most U.S. cities and suburbs are not designed to promote safe walking or bicycling, but rather favor the convenience of automobile travel. Moreover, this generation of children are faced with multiple media sources, including television, computers, and ever-appealing video games.

Taken together, these environmental conveniences that signify growth and development of society, favor over-consumption, while simultaneously reducing the energy required to perform daily activities. Our genes, some of which were selected for during times of famine and food scarcity, are now faced with survival in a time of unparalleled food surplus. Because we evolved when food environments were much different than they are today, we continue to be much more efficient at holding onto calories than we are at expending them. All of these effects, in concert, have contributed to the current obesity epidemic.