The natural history of the development of Obesity in a cohort of young U.S. Adults between 1981 and 1998
Summary written by Kevin Fontaine, Ph.D.
The prevalence of overweight and obesity is increasing at an alarming rate. From 1960 to 1999 the rates of overweight (body mass index [BMI] > 25 kg/m2) increased from 44% to 61% and the prevalence of obesity (BMI > 30 kg/m2) from 13% to 27%. This is of particular concern because obesity is strongly associated with a variety of health problems including hypertension, hypercholesterolemia, heart disease, Type 2 diabetes, some forms of cancer, and osteoarthritis of the knee, hip, and hands. Moreover, it is estimated that between 280,000 and 325,000 deaths a year in the United States are attributable to obesity. Thus, understanding how obesity develops overtime, and who is at greatest risk, and when that risk is greatest is vital in public health efforts to reverse the trend toward obesity.
Methods: Using data from the National Longitudinal Study of Youth, including self-reported height and weight data collected 12 times from the same individuals between 1981 and 1998, McTigue and colleagues (Ann Intern Med. 2002;136:857-864) identified predictors of obesity at ages 35 to 37.
Results: Of the 9,179 persons completing all 12 assessments, 28% of the women and 26% of the men were obese by age 35 to 37 years. The onset of obesity was 2.1 times faster for black women and 1.5 times faster for Hispanic women compared to white women. For men, obesity developed 2.5 times faster among Hispanic men compared to white men. After the age of 28, black men developed obesity 2.4 times faster than white men after the age of 28.
Summary: There were marked ethnic differences observed in the rates of developing obesity in young US adults. Black persons had the highest odds for obesity onset, followed by Hispanic persons and white persons.
Editorial Comment: The findings of this study are both clear and worrisome: a greater proportion of US adults are becoming obese each year, and the onset of obesity is occurring at younger ages, especially among black and Hispanic persons. Given this, we can expect to observe a continued escalation in the prevalence of obesity-associated health problems, as well as the onset of these health problems at younger and younger ages. Obesity is well-established risk factor for osteoarthritis of the knee, hip, and hand thus, based on the findings of this study; we can expect to witness a marked increase in the prevalence of obesity-associated osteoarthritis. Perhaps, to some extent, we are already beginning to observe this in that since 1990, the prevalence of arthritis has increased by 750,000 cases per year. In any event, it is clear that altering the course of obesity in the United States, especially among minority ethnic groups, is vital if we are to stem the tide of obesity-related morbidity and mortality.