Q & A's on Overweight and Obesity

What is the difference between overweight and obesity?
There are various methods to determine whether a person is overweight or obese, but the most commonly used is body mass index (BMI). BMI is calculated by dividing a person’s body weight (in kg) by the square of the height in meters. In adults, overweight is defined as a body mass index (BMI) of 25 to 29.9, and obesity is defined as a BMI of 30 or greater. For perspective, a man six feet tall would be overweight if he weighed 185 pounds or more, and obese if he weighed 220 pounds or more. A woman 5 feet 4 inches tall, weighing 145 pounds or greater, would be considered overweight, and at 175 pounds or greater would be considered obese.

What is the prevalence of overweight and obesity in the U.S.?
The increasing trend of overweight and obesity in the U.S. is staggering. From the results of the 1999–2000 National Health and Nutrition Examination Survey, 64 percent of the adult population is overweight. About half of those people are obese, representing a doubling in the prevalence of obesity in only about 20 years.

Is there a problem with overweight in children?
From 1999-2000 data, about 30 percent of children and adolescents ages 6 to 19 years old are overweight or at risk of overweight. About half of these children are overweight, representing a doubling to tripling of the prevalence of overweight in these age groups in the past two decades. The rates of overweight and at risk of overweight are even higher among minorities and economically disadvantaged children. For example, the rates of overweight and at risk of overweight exceed 40 percent among 12-19 year old non-Hispanic blacks and Mexican Americans.

Is the problem of overweight and obesity limited to the U.S.?
No. Overweight and obesity have become a global epidemic in approximately the past 20 years. The World Health Organization estimates that there are one billion overweight and obese people in the world today, with about 300 million of them being obese. Although the problem is most severe in developed countries, it is not limited to the developed world, as evidenced by the fact that “under-nutrition” and “over-nutrition” co-exist in developing countries.

Are overweight and obesity just cosmetic issues?
No. Excess body weight is strongly associated with type 2 diabetes, cardiovascular disease, cancer, arthritis, breathing disorders, and psychiatric disorders, such as depression. The prevalence of these obesity-related diseases has also increased at an alarming rate. For example, until recently, type 2 diabetes was rare in children, but its prevalence has been rising along with that of overweight and obesity in children. Further, according to the U.S. Surgeon General, about 300,000 deaths per year in the U.S. are attributable to obesity, and obese individuals have a 50–100 percent increased risk of premature death from all causes, compared to people with a healthy body weight.

What causes obesity?
Although some have sought to lay blame for this epidemic on single factors such as eating at fast food restaurants, “supersizing” of food portions, and food advertising directed at children, overweight and obesity are very complex. Numerous factors, such as genetics, metabolism, behavior, the environment, culture, and socioeconomic class, affect body weight. There are a few genetic diseases that are associated with obesity; however, body weight is usually a matter of balancing the energy equation of calories consumed (eating) and calories expended (physical activity).

What is the best way to treat overweight and obesity?
According to the U.S. Surgeon General, even a modest weight loss of about 5–15 percent of body weight by overweight and obese individuals can reduce the risk for some diseases, especially cardiovascular disease. However, weight loss and especially maintenance of weight loss are major challenges; there is no “magic bullet.” The standard of weight loss programs has been a multidisciplinary approach including low calorie diets, exercise, and behavior modification. Although there are a number of weight reduction diets available today, most nutrition experts agree that it is the reduction in calories in all of these diets that is responsible for weight loss. Sadly, no matter what the diet, most patients eventually regain the lost weight.

What is Exponent doing to work on the overweight and obesity problem?
Recognizing the daunting task ahead and the critical need for scientific and public policy answers, Exponent has assembled a multidisciplinary team to work with clients on a comprehensive approach to the overweight and obesity crisis. In addition to conducting critical research, the Exponent team can review, interpret, and integrate the massive amount of existing and developing research, and can provide comprehensive and clear reports and presentations that explain apparent differences in research results, gaps in the research, and application of the results to addressing the overweight and obesity crisis. Exponent can also conduct medical economics and health and productivity evaluations. Because overweight and obesity are global issues, Exponent has developed networks of key opinion leaders in scientific and medical disciplines in countries around the world, to work with clients on local issues related to obesity.

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