ANN ARBOR— Effective worksite weight control programs could bring about substantial savings in medical costs for employers and help prevent overweight- and obesity-related diseases, University of Michigan Health Management Research Center research shows.

The study of 177,971 employees, retirees and adult dependents of General Motors Corp. showed a consistent relationship between medical costs and progressively higher categories of overweight and obesity, according to HMRC lead author Fei-Fei Wang and Senior Research Analyst Shirley Musich.

“The median medical cost for healthy weight people was $2,225, compared with $2,388 for the next category of overweight and $3,753 for the most extreme obesity category. Except for the underweight group, medical costs gradually increase as weight increases,” Musich said. The study, published in January’s American Journal of Health Promotion, is the first to examine the relationship between median medical costs and the six weight groups defined by the National Heart, Lungs and Blood Institute in 1998.

The NHLB weight guidelines use body mass index or BMI, which calculates weight in kilograms, divided by height in meters squared. According to BMI measures across gender and age, 55 percent of American adults, or 97 million people, are classified as overweight or obese, Musich said. In the General Motors study population, 40 percent were overweight and more than 21 percent were obese. Healthy weight employees made up 37 percent of the population, and less than 2 percent were underweight.

“Being overweight was more prevalent in men than women in this study: 46 percent of the males were overweight compared with 33 percent of the females. However in the obese category, the prevalence was approximately the same: 22 percent for females and 21 percent for males. “For the most part, the median costs increased as BMI increased regardless of age or gender,” Musich said. “The relationship between BMI levels and costs was only unclear for the oldest males in the study, ages 75 and older.” The data was collected over two years ending in 1998.

“While there is a concern that some people — especially those who are overweight — tend to understate their weight, a cross-check of those who had follow-up screenings showed that the margin of error was minimal,” Musich said. Further, an underestimation of BMI would put even more people into the high weight/ high cost category. In 1994, researchers conservatively estimated the direct medical costs of obesity in the United States at over $51 billion. Obesity has been clearly associated with many diseases such as type II diabetes, coronary heart disease, hypertension, stroke and some forms of cancer. 

The authors conclude that, “Helping people control and even lose weight could improve their health status and reduce risk of disease, and in the process reduce the overall burden of health care costs for corporations and other payers.” For further information, contact lead author Shirley Musich (734) 763-2462 smusich@umich.edu