The Obesity Epidemic

Overweight and obesity are growing problems. These conditions have reached epidemic proportions in the United States and in most industrialized nations around the world. An explosion in the variety and availability of high-calorie, high-fat convenience foods and the fact that people are exercising less and performing less manual labor have added to the problem. All of the social stigmas involved with being overweight may lead to improper use of aids designed to decrease weight. Once they have decided to lose weight, adolescents, just like adults, want to lose excess weight as quickly as possible and may do so in ways that are not healthy and do not lead to maintenance of weight loss over a long period of time.

Most people believe someone is obese if they look “fat.” This is not true. Health-care professionals and scientists have developed specific definitions for the words overweight and obese.Overweight and obesity are not determined solely by an individual’s weight, but are defined in terms of a person’s weight relative to his or her height. Doctors and researchers use a special set of measurements and mathematical formulas to determine whether a person is overweight or obese.

The body mass index (BMI) is a number calculated from a person’s weight and height that can be used to estimate his or her level of body fat. A person is classified as healthy, overweight, or obese based on his or her BMI. The BMI value can be helpful in assessing the health risks a person may face because he or she is carrying too much weight. A person’s BMI is reported as kg/m2 (Figure 1.1). Adults with a BMI of 25 to 29.9 kg/m2 are considered overweight. Adults with a BMI over 30 kg/m2 are considered obese. Being overweight and obese are not mutually exclusive; all obese individuals are also considered overweight. A measurement called the percentile of BMI is used to identify overweight and obesity in children and adolescents. The Centers for Disease Control and Prevention (CDC), an organization that defines the healthy height and weight information for growing children that is found on national growth charts, avoids using the word obesity for children and adolescents. The CDC chooses not to use the word obese because children are still growing and may “grow into” their weight. Instead, the CDC suggests two levels into which overweight or obese children can be placed:

1. The 85th percentile, defining those who are at risk for
becoming obese.
2. The 95th percentile, the more severe level used to
describe children who are already obese.

BMI (and percentile of BMI) is only one factor in determining a person’s weight-related health risk. Having a BMI in the “healthy” range does not necessarily mean that a person is fit and healthy. BMI does not take into account lean body mass or body frame. A muscular, large-framed person’s BMI could indicate that he or she is obese, but other factors would show that this is not the case.

The presence of excess fat in the stomach area is also a negative factor to be considered in overweight individuals. People who have fat in the abdomen that is out of proportion to their total body fat have what is called central obesity. A person with central obesity is defined as having a circumference, or distance around the waist, of greater than 40 inches in adult men and greater than 35 inches in adult women. Studies have shown that people with central obesity have a higher risk of weight-related health problems than do people whose body fat is more evenly distributed. The reason for this is not known, but health studies have shown that there is a significant increase in heart problems in people with central obesity.