Primary Pulmonary Hypertension News - Menu Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults - PDF Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults Executive Summary Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults This report targets primary care practitioners and provides evidence for the effects of treatment on overweight and obesity. It is based on the systematic review of the published scientific literature to address 35 key clinical questions on how different treatment strategies affect weight loss and how weight control affects the major risk factors for heart disease and stroke. 228 pages. NIH Publication No. 98-4083 The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults **Final Version** You may obtain the document: View online (in formats below) PDF document, Full Color, 1.5 MB NATIONAL INSTITUTES OF HEALTH FOR RELEASE CONTACT: NHLBI Communications Office First Federal Obesity Clinical Guidelines Released The first Federal guidelines on the identification, evaluation, and treatment of overweight and obesity in adults were released today by the National Heart, Lung, and Blood Institute (NHLBI), in cooperation with the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). These clinical practice guidelines are designed to help physicians in their care of overweight and obesity, a growing public health problem that affects 97 million American adults -- 55 percent of the population. 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 total costs attributable to obesity-related disease approaches $100 billion annually. "Overweight and obesity pose a major public health challenge. The development of these guidelines was a pioneering achievement since they were the first ever developed by the Institute using an evidence-based model and methodology," said NHLBI Director Dr. Claude Lenfant. "This report will be an invaluable clinical tool for any health care professional who works with overweight or obese patients," he added. The guidelines are based on the most extensive review of the scientific evidence on overweight and obesity conducted to date. The review involved a systematic analysis of the published scientific literature to address 35 key clinical questions on how different treatment strategies affect weight loss and how weight control affects the major risk factors for heart disease and stroke as well as other chronic diseases and conditions. The guidelines 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 24-member expert panel that developed the guidelines identified 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, and supports the Dietary Guidelines for Americans issued in 1995. 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 BMI numbers apply to both men and women. Some very muscular people may have a high BMI without health risks. The panel recommends that BMI be determined in all adults. People of normal weight should have their BMI reassessed in 2 years. "The evidence is solid that the risk for various cardiovascular and other diseases rises significantly when someone's BMI is over 25 and that risk of death increases as the body mass index reaches and surpasses 30," said Dr. F. Xavier Pi Sunyer, chairman of the expert panel and director of the Obesity Research Center, St. Luke's/Roosevelt Hospital Center in New York City. "The guidelines tell the truth about the risks associated with unhealthy weight. We hope that physicians and the public will take the message seriously and use the guidelines to begin to deal effectively with a difficult problem," asserted Dr. Pi-Sunyer. 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 in the highest obesity category have more than twice the risk of hypertension, high blood cholesterol, or both compared to men of normal weight. Women in the highest obesity category have four times the risk of either or both of these risk factors. 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. Overweight patients without risk factors should prevent further weight gain, advise the guidelines. In addition to measuring BMI, health care professionals should evaluate a patient's risk factors, such as elevations in blood pressure or blood cholesterol, 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. 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. According to the guidelines, the most successful strategies for weight loss include calorie reduction, increased physical activity, and behavior therapy designed to improve eating and physical activity habits. Other recommendations include: Patients should engage in moderate physical activity, progressing to 30 minutes or more on most or preferably all days of the week. Reducing dietary fat alone--without reducing calories--will not produce weight loss. Cutting back on dietary fat can help reduce calories and is heart-healthy. The initial goal of treatment should be to reduce body weight by about 10 percent from baseline, an amount that reduces obesity-related risk factors. With success, and if warranted, further weight loss can be attempted. A reasonable time line for a 10 percent reduction in body weight is six months of treatment, with a weight loss of 1 to 2 pounds per week. Weight-maintenance should be a priority after the first 6 months of weight-loss therapy. Physicians should 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 risk factors) who have been unable to lose weight or maintain weight loss with conventional nondrug therapies. Drug therapy may 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. Weight loss surgery is an option for carefully selected patients with clinically severe obesity -- BMI of > 40 or BMI of >35 with coexisting conditions when less invasive methods have failed and the patient is at high risk for obesity-associated illness. Lifelong medical surveillance after surgery is a necessity. Overweight and obese patients who do not wish to lose weight, or are otherwise not candidates for weight loss treatment, should be counseled on strategies to avoid further weight gain. Age alone should not preclude weight loss treatment in older adults. A careful evaluation of potential risks and benefits in the individual patient should guide management. According to NHANES III, the trend in the prevalence of overweight and obesity is upward. The guidelines note that from 1960 to 1994, the prevalence of obesity in adults (BMI >30) increased from nearly 13 percent to 22.5 percent of the U.S. population, with most of the increase occurring in the 1990s. "There are several possible reasons for the increase," asserted Karen Donato, coordinator of the Obesity Education Initiative. "When people read labels, they're more likely to notice what's lowfat and healthy' but may not be looking at calories. Also, more people are eating out and portion sizes have increased. Another issue is decreased physical activity. So people are consuming more calories and are less active. It doesn't take much to tip the energy balance," she said. The upward trend in adult obesity has also been observed in children, notes the report. Since treatment issues surrounding overweight children and adolescents are quite different from the treatment of adults, the panel called for a separate guideline for youth as soon as possible. However, a healthy eating plan and increased physical activity is an important goal for all family members. With that in mind, the guidelines contain practical information on healthy eating. Based on this material, the NHLBI has developed consumer tips on shopping, eating, and dining out. The guidelines have been reviewed by 115 health experts at major medical and professional societies. They have been endorsed by the coordinating committees of the National Cholesterol Education Program and the National High Blood Pressure Education Program, the North American Association for the Study of Obesity, the NIDDK Task force on the Prevention and Treatment of Obesity, and the American Heart Association. These groups represent 54 professional societies, government agencies, and consumer organizations. 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 is available on the NHLBI Website. Single free copies of the consumer tips referred to above are available by writing to the NHLBI Information Center, P.O. Box 30105, Bethesda, MD 20824-0105. Introduction While there is agreement about the health risks of overweight and obesity, there is less agreement about their management. Some have argued against treating obesity because of the difficulty in maintaining long-term weight loss and of potentially negative consequences of the frequently seen pattern of weight cycling in obese subjects. Others argue that the potential hazards of treatment do not outweigh the known hazards of being obese. To consider these issues, the National Heart, Lung, and Blood Institute's Obesity Education Initiative in cooperation with the National Institute of Diabetes and Digestive and Kidney Diseases convened the Expert Panel on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults in May 1995. Demographic Variations in Overweight and Obesity Prevalence The prevalence of overweight and obesity is generally higher for men and women in racial-ethnic minority populations than in U.S. whites, with the exception of Asian-Americans, for whom overweight and obesity prevalence is lower than in the general population (51). In the 1982-1984 HHANES, the age-adjusted prevalence of a BMI of 27.3 in Puerto Rican women was 40 percent (27). The Strong Heart Study reported the average prevalence of overweight using BMI 27.8 or 27.3 for men and women, respectively, in three groups of American Indians studied during 1988 and1989 as follows: in Arizona, 67 percent of the men and 80 percent of the women; in Oklahoma, 67 percent of the men and 71 percent of the women; and in South Dakota and North Dakota, 54 percent of the men and 66 percent of the women (52). Women in the United States with low incomes or low education are more likely to be obese than those of higher socioeconomic status; the association of socioeconomic status with obesity is less consistent in men (53). Obesity is less common after the age of 70 among both men and women, possibly due to a progressive decrease in BMI with increasing age past the fifth decade or to an excess in mortality associated with increasing BMI in the presence of increasing age (1). Morbidity The nature of obesity-related health risks is similar in all populations, although the specific level of risk associated with a given level of overweight or obesity may vary with race/ethnicity, and also with age, gender, and societal conditions. For example, the absolute risk of morbidity in chronic conditions such as CHD is highest in the aged population, while the relative risk of having CHD in obese versus nonobese individuals is highest in the middle adult years (129-131). A high prevalence of diabetes mellitus in association with obesity is observed consistently across races/ethnicities, while the relative prevalence of hypertension and CHD in obese versus nonobese populations varies between groups. The health risks of overweight and obesity are briefly described in the next sections. Hypertension Figure 2. NHANES III Age-Adjusted Prevalence of * Defined as mean systolic blood pressure 140mm Hg, mean diastolic as 90mm Hg or currently taking anti-hypertensive medication. High blood pressure is defined as mean systolic blood pressure 140 mm Hg, or mean diastolic blood pressure 90 mm Hg, or currently taking anti-hypertensive medication. The prevalence of high blood pressure in adults with BMI 30 is 38.4 percent for men and 32.2 percent for women, respectively, compared with 18.2 percent for men and 16.5 percent for women with BMI < 25, a relative risk of 2.1 and 1.9 for men and women, respectively. The direct and independent association between blood pressure and BMI or weight has been shown in numerous cross-sectional studies (3-5), including the large international study of salt (INTERSALT) carried out in more than 10,000 men and women (6). INTERSALT reported that a 10 kg (22 lb) higher body weight is associated with 3.0 mm Hg higher systolic and 2.3 mm Hg higher diastolic blood pressure (6). These differences in blood pressure translate into an estimated 12 percent increased risk for CHD and 24 percent increased risk for stroke (132). Positive associations have also been shown in prospective studies (76-80). Obesity and hypertension are comorbid risk factors for the development of cardiovascular disease. The pathophysiology underlying the development of hypertension associated with obesity includes sodium retention and associated increases in vascular resistance, blood volume, and cardiac output. These cardiovascular abnormalities associated with obesity are believed to be related to a combination of increased sodium retention, increased sympathetic nervous system activity, alterations of the renin-angiotensin system and insulin resistance. The precise mechanism whereby weight loss results in a decrease in blood pressure is unknown. However, it is known that weight loss is associated with a reduction in vascular resistance and total blood volume and cardiac output, an improvement in insulin resistance, a reduction in sypathetic nervous system activity, and suppression of the activity of the renin angiotensin aldosterone system (764-769). Stroke More recently published reports (12, 13) are based on larger samples and delineate the importance of stroke subtypes in assessing these relationships. They also attempt to capture all stroke events, whether fatal or nonfatal. These studies suggest distinct risk factors for ischemic stroke as compared to hemorrhagic stroke, and found overweight to be associated with the former, but not the latter. This may explain why studies that use only fatal stroke outcomes (and thus overrepresent hemorrhagic strokes) show only weak relationships between overweight and stroke. These recent prospective studies demonstrate that the risk of stroke shows a graded increase as BMI rises. For example, ischemic stroke risk is 75 percent higher in women with BMI > 27, and 137 percent higher in women with a BMI > 32, compared with women having a BMI < 21 (12). Congestive Heart Failure Obesity can result in alterations in cardiac structure and function even in the absence of systemic hypertension or underlying heart disease. Ventricular dilatation and eccentric hypertrophy may result from elevated total blood volume and high cardiac output. Diastolic dysfunction from eccentric hypertrophy and systolic dysfunction from excessive wall stress result in so-called "obesity cardiomyopathy" (172, 173). The sleep apnea/obesity hyperventilation syndrome occurs in 5 percent of severely obese individuals, and is potentially life-threatening. Extreme hypoxemia induced by obstructive sleep apnea syndrome may result in heart failure in the absence of cardiac dysfunction (174).
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