A large, community-based study -- considered the first study to assess the long-term risk of developing overweight and obesity in adults -- found that over 30 years, nine out of 10 men and seven out of 10 women were overweight or became overweight. In addition, more than one in three were obese or became obese.
The study was supported by the National Heart, Lung, and Blood Institute (NHLBI), one of the National Institutes of Health (NIH).
Researchers analyzed the short-term and long-term chances of developing overweight and obesity among more than 4,000 white adults enrolled in the offspring cohort of NHLBI's landmark Framingham Heart Study, an ongoing longitudinal study in Framingham, Massachusetts. Participants ages 30 to 59 were followed for 30 years, from 1971 to 2001. The results appear in the October 4, 2005, issue of the Annals of Internal Medicine.
"National surveys and other studies have told us that the United States has a major weight problem, but this study suggests that we could have an even more serious degree of overweight and obesity over the next few decades," said NHLBI Director Elizabeth G. Nabel, M.D., who also co-chairs the NIH Obesity Research Task Force. "In addition, these results may underestimate the risk for some ethnic groups."
Framingham participants were white, and other studies have shown, for example, that Hispanic and black individuals, especially women, have a greater prevalence of excess weight compared to their white counterparts.
According to the National Center for Health Statistics, part of the Centers for Disease Control and Prevention, 65 percent of U.S. adults aged 20 years and older are either overweight or obese, and approximately 30 percent of adults are obese. These estimates are from the 1999-2002 National Health and Nutrition Examination Survey, a population-based survey.
Framingham researchers assessed the participants' body mass index (BMI) -- a standard measure of weight relative to height, which is an indicator of total body fat. A BMI of 18.5 to 24.9 kg/m2 is considered a normal, or healthy, weight for adults. Overweight is a BMI of 25 to 29.9 kg/m2, and obesity is a BMI of 30 kg/m2 or higher.
Making it to middle age without extra pounds was no guarantee for staying at a healthy weight -- even in the short term. About one in five women and one in four men who were at a healthy BMI at a routine Framingham study examination became overweight after four years. Among those who were overweight, 16 to 23 percent of women and 12 to 13 percent of men became obese within four years.
"Our results, although not surprising, are worrisome," comments Ramachandran Vasan, M.D., Associate Professor of Medicine at Boston University School of Medicine and lead author of the study. "If the trend continues, our country will continue to face substantial health problems related to excess weight."
"Overweight and obesity increase the risk of poor health. We hope these results will serve as a wake-up call to Americans of all ages," adds Nabel. "Even those who are now at a healthy weight need to be careful about maintaining energy balance to avoid gaining weight. Taking simple steps to make sure that the overall the number of calories you consume do not exceed the amount you burn can play a major role in lowering your risk for many chronic conditions."
Overweight increases the likelihood of developing diabetes, high blood pressure and heart disease, stroke, breathing problems such as asthma and sleep apnea, some cancers, osteoarthritis, and gall bladder disease. Obesity is associated with these conditions as well as with early death. Research has shown that even a small weight loss (just 10 percent of body weight) can help people who are overweight or obese lower their risk of developing many of these conditions.
The Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults recommend that both people who are overweight as well as those who are at a healthy weight prevent weight gain. The guidelines are available online at http://www.nhlbi.nih.gov/guidelines/obesity/ob_home.htm.
Strategies that promote a healthy weight beginning in childhood are critical. For information on We Can!, NIH's national education program to enhance children's activity and nutrition to prevent childhood obesity, visit the website at http://wecan.nhlbi.nih.gov or call toll-free 866-35-WECAN.
For help assessing obesity risk and advice on how to lose weight, consult your healthcare professional.