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
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 -- http://www.nhlbi.nih.gov/nhlbi/
on June 17.