The first Federal guidelines on the identification, evaluation, and treatment of overweight and obesity in adults are scheduled to be released on June 17 by the National Heart, Lung, and Blood Institute (NHLBI), in cooperation with the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Due to a premature release in the news media of erroneous information about the guidelines, some of the key recommendations of the report are being released now. The intent is to ensure that accurate information about the guidelines is available to the public.
The guidelines were developed by a 24- member expert panel chaired by Dr. F. Xavier Pi-Sunyer, director of the Obesity Research Center, St.Luke's/Roosevelt Hospital Center in New York City. They are currently being reviewed by 115 health experts at major medical and professional societies. The NHLBI is in the process of receiving comments and endorsements from these experts.
Based on the most extensive review of the scientific evidence on overweight and obesity conducted to date, these clinical practice guidelines for physicians present a new approach for the assessment of overweight and obesity and establish principles of safe and effective weight loss.
According to the guidelines, assessment of overweight involves evaluation of three key measures--body mass index (BMI), waist circumference, and a patient's risk factors for diseases and conditions associated with obesity.
The guidelines' definition of overweight is based on research which relates body mass index to risk of death and illness. The expert panel that developed the guidelines defined overweight as a BMI of 25 to 29.9 and obesity as a BMI of 30 and above, which is consistent with the definitions used in many other countries. BMI describes body weight relative to height and is strongly correlated with total body fat content in adults. According to the guidelines, a BMI of 30 is about 30 pounds overweight and is equivalent to 221 pounds in a 6' person and to 186 pounds in someone who is 5'6".
The panel recommends that BMI be determined in all adults. People of normal weight should have their BMI reassessed in 2 years.
According to a new analysis of the National Health and Nutrition Examination Survey (NHANES III), as BMI levels rise, average blood pressure and total cholesterol levels increase and average HDL or good cholesterol levels decrease. Men and women in the highest obesity category have five times the risk of hypertension, high blood cholesterol, or both compared to individuals of normal weight.
The guidelines recommend weight loss to lower high blood pressure, to lower high total cholesterol and to raise low levels of HDL or good cholesterol, and to lower elevated blood glucose in overweight persons with two or more risk factors and in obese persons who are at increased risk. They recommend that overweight patients without risk factors work on maintaining current weight or preventing further weight gain.
According to the guidelines, 97 million American adults -- 55 percent of the population -- are now considered overweight or obese. These individuals are at increased risk of illness from hypertension, lipid disorders, type 2 diabetes, coronary heart disease, stroke, gallbladder disease, osteoarthritis, sleep apnea and respiratory problems, and certain cancers. The report of the guidelines also notes that obesity is associated with higher death rates and, after smoking, is the second leading cause of preventable death in the U.S. today. The total costs attributable to obesity-related disease approaches $100 billion annually.
In addition to measuring BMI, health care professionals can assess an individual patient's risk status through evaluating risk factors for obesity, such as elevations in blood pressure or family history of obesity-related disease. At a given level of overweight or obesity, patients with additional risk factors are considered to be at higher risk for health problems, requiring more intensive therapy and modification of any risk factors.
Physicians are also advised to determine waist circumference, which is strongly associated with abdominal fat. Excess abdominal fat is an independent predictor of disease risk. The panel concluded that waist circumference is a better marker of abdominal fat and a better predictor of disease risk than the current method of calculating the waist-to-hip ratio. A waist circumference of over 40 inches in men and over 35 inches in women signifies increased risk in those who have a BMI of 25 to 34.9.
The new guidelines stress that there are no new or magic cures for weight loss. The most successful strategies for weight loss include calorie reduction, increased physical activity, and behavior therapy designed to improve eating and physical activity habits. The guidelines advise physicians to have their patients try lifestyle therapy for at least 6 months before embarking on physician-prescribed drug therapy. Weight loss drugs approved by the FDA for long-term use may be tried as part of a comprehensive weight loss program that includes dietary therapy and physical activity in carefully selected patients (BMI >30 without additional risk factors, BMI >27 with two or more of the following risk factors--diabetes, high blood pressure, high blood cholesterol, and sleep apnea) who have been unable to lose weight or maintain weight loss with conventional nondrug therapies. Drug therapy can also be used during the weight maintenance phase of treatment. However, drug safety and effectiveness beyond one year of total treatment have not been established.
When published, Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults will be distributed to primary care physicians in the U.S. as well as to other interested health care practitioners. It will also be available on the NHLBI website on June 17.