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  1. 1. Obesity Education Initiative CLINICAL GUIDELINES ON THE I D E N T I F I C AT I O N , E V A L U AT I O N , AND T R E AT M E N T OF OVERWEIGHT AND OBESITY IN A D U LT S Th e Evide nce Repor t N A T I O N A L I N S T I T U T E S O F H E A L T H N A T I O N A L H E A R T , L U N G , A N D B L O O D I N S T I T U T E
  2. 2. CLINICAL GUIDELINES ON THE I D E N T I F I C AT I O N , E V A L U AT I O N , AND T R E AT M E N T OF OVERWEIGHT AND OBESITY IN A D U LT S The Ev i d e nc e Re p o r t NIH P U B L I C AT I O N N O . 98- 4083 S E P T E M B E R 199 8 N AT I O N A L I N S T I T U T E S OF H E A LT H Na tiona l Hea r t , Lu n g , a nd Blood Insti tu te in c oop era tion wit h The Na tiona l In s titu te o f Dia betes a nd Dig es tive a n d Kidney Disea ses
  3. 3. NHLBI Obesity Education Initiative Expert Panel on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults F. Xavier Pi-Sunyer, M.D., M.P.H. William H. Dietz, M.D., Ph.D. Chair of the Panel Director Chief, Endocrinology, Diabetes, and Nutrition Division of Nutrition and Physical Activity Director, Obesity Research Center National Center for Chronic Disease Prevention St. Luke's/Roosevelt Hospital Center and Health Promotion Professor of Medicine Centers for Disease Control and Prevention Columbia University College of Physicians and Atlanta, GA Surgeons New York, NY John P. Foreyt, Ph.D. Professor of Medicine and Director Diane M. Becker, Sc.D., M.P.H. Nutrition Research Clinic Director Baylor College of Medicine Center for Health Promotion Houston, TX Associate Professor Department of Medicine Robert J. Garrison, Ph.D. The Johns Hopkins University Associate Professor Baltimore, MD Department of Preventive Medicine University of Tennessee, Memphis Claude Bouchard, Ph.D. Memphis, TN Professor of Exercise Physiology Physical Activity Sciences Scott M. Grundy, M.D., Ph.D. Laboratory Director Laval University Center for Human Nutrition Sainte Foy, Quebec University of Texas CANADA Southwestern Medical Center at Dallas Dallas, TX Richard A. Carleton, M.D. Professor of Medicine Barbara C. Hansen, Ph.D. Brown University School of Medicine Professor of Physiology Pawtucket, RI Director of Obesity and Diabetes Research Center University of Maryland School of Medicine Graham A. Colditz, M.D., Dr.P.H. Baltimore, MD Associate Professor of Medicine Harvard Medical School Millicent Higgins, M.D. Channing Laboratory Department of Epidemiology Boston, MA School of Public Health University of Michigan Ann Arbor, MI ii
  4. 4. James O. Hill, Ph.D. Albert P. Rocchini, M.D. Associate Director of Research Chief of Cardiology Center for Human Nutrition University of Michigan Medical Center University of Colorado Health Sciences Center Ann Arbor, MI Denver, CO Philip L. Smith, M.D. Barbara V. Howard, Ph.D. Professor of Medicine President Division of Pulmonary and Critical Care Medlantic Research Institute Medicine Washington, DC The Johns Hopkins Asthma and Allergy Center Baltimore, MD Robert C. Klesges, Ph.D. Professor Linda G. Snetselaar, Ph.D., R.D. University of Memphis Prevention Center Associate Professor University of Memphis Head of Preventive Nutrition Education Memphis, TN Department of Preventive Medicine University of Iowa Robert J. Kuczmarski, Dr.P.H., R.D. Iowa City, IA Nutrition Analyst National Center for Health Statistics James R. Sowers, M.D. Centers for Disease Control and Prevention Professor of Medicine and Physiology Hyattsville, MD Director Division of Endocrinology, Metabolism, and Shiriki Kumanyika, Ph.D., R.D., M.P.H. Hypertension Professor and Head Wayne State University School of Medicine Department of Human Nutrition and Dietetics University Health Center The University of Illinois at Chicago Detroit, MI Chicago, IL Michael Weintraub, M.D. R. Dee Legako, M.D. Director Prime Care Canyon Park Family Physicians, Inc. Office of Drug Evaluation V Edmond, OK Food and Drug Administration Rockville, MD T. Elaine Prewitt, Dr.P.H., R.D. Assistant Professor David F. Williamson, Ph.D., M.S. Department of Preventive Medicine and Epidemiologist Epidemiology Division of Diabetes Translation Loyola University Medical Center Centers for Disease Control and Prevention Maywood, IL Chamblee, GA iii
  5. 5. G. Terence Wilson, Ph.D. Van S. Hubbard, M.D., Ph.D. Oscar K. Buros Professor of Psychology Director, NIH Division of Nutrition Research Director, Rutgers Eating Disorders Clinic Coordination Piscataway, NJ Chief, Nutritional Sciences Branch National Institute of Diabetes and Digestive and Kidney Diseases Ex-Officio Members National Institutes of Health Bethesda, MD Clarice D. Brown, M.S. Project Manager James P. Kiley, Ph.D.* CODA Research, Inc. Director Silver Spring, MD Airway Biology and Disease Program Division of Lung Diseases Karen A. Donato, M.S., R.D.* National Heart, Lung, and Blood Institute Executive Director of the Panel National Institutes of Health Coordinator Bethesda, MD NHLBI Obesity Education Initiative National Heart, Lung, and Blood Institute Eva Obarzanek, Ph.D., R.D., M.P.H.* National Institutes of Health Research Nutritionist Bethesda, MD Prevention Scientific Research Group Division of Epidemiology and Clinical Nancy Ernst, Ph.D., R.D.* Applications Nutrition Coordinator National Heart, Lung, and Blood Institute Office of the Director National Institutes of Health Division of Epidemiology and Clinical Applications Bethesda, MD National Heart, Lung, and Blood Institute National Institutes of Health Bethesda, MD Consultant D. Robin Hill, Ph.D.* David Schriger, M.D., M.P.H., F.A.C.E.P. Social Science Analyst Associate Professor Behavioral Medicine Branch UCLA Emergency Medicine Center Division of Epidemiology and Clinical University of California at Los Angeles Applications School of Medicine National Heart, Lung, and Blood Institute Los Angeles, CA National Institutes of Health Bethesda, MD San Antonio Cochrane Center Michael J. Horan, M.D., Sc.M.* Director Elaine Chiquette, Pharm.D. Division of Heart and Vascular Diseases V.A. Cochrane Center at San Antonio National Heart, Lung, and Blood Institute Audie L. Murphy Memorial Veterans Hospital National Institutes of Health San Antonio, TX Bethesda, MD * NHLBI Obesity Education Initiative Task Force Members iv
  6. 6. Cynthia Mulrow, M.D., M.Sc. V.A. Cochrane Center at San Antonio Audie L. Murphy Memorial Veterans Hospital San Antonio, TX Staff Adrienne Blount, B.S. R.O.W. Sciences, Inc. Rockville, MD Maureen Harris, M.S., R.D. R.O.W. Sciences, Inc. Rockville, MD Anna Hodgson, M.A. R.O.W. Sciences, Inc. Rockville, MD Pat Moriarty, M.Ed., R.D. R.O.W. Sciences, Inc. Rockville, MD The panel acknowledges the assistance of Dr. Rashid Chotani, Johns Hopkins University; Dr. Robert Klesges, University of Memphis; Dr. Walter Pories, East Carolina University; Dr. Ivan Baines, NHLBI; Dr. Christine Kelly, NHLBI; Glen Bennett, NHLBI; Dr. Fred Heydrick, BioReview; Debbie Lurie, Prospect Associates; Estelle Schwalb, Prospect Associates; Lori McCray, R.O.W. Sciences, Inc.; and Niyati Pandya, R.O.W. Sciences, Inc. v
  7. 7. Contents Foreword vii 2. Classification of Overweight and Executive Summary xi Obesity 58 C. Assessment of Risk Status 62 1. Introduction 1 D. Evaluation and Treatment Strategy 65 A. Rationale for Guidelines Development 1 E. Exclusion from Weight Loss Therapy 70 B. Objectives of the Guidelines 2 F. Patient Motivation 70 C. Guideline Development Methodology 2 G. Goals of Weight Loss and D. Statement of Assumptions 5 Management 71 E. Intended Users of These Guidelines 5 1. Weight Loss 71 2. Weight Maintenance at 2. Overweight and Obesity: Background 6 Lower Weight 72 A. Health and Economic Costs 6 3. Prevention of Further Weight Gain 73 1. Prevalence and Time Trends 6 H. Strategies for Weight Loss and 2. Demographic Variations in Weight Maintenance 73 Overweight and Obesity Prevalence 9 1. Dietary Therapy 73 3. Economic Costs of Overweight 2. Physical Activity 77 and Obesity 9 3. Behavior Therapy 81 B. Prevention of Overweight and Obesity 11 4. Combined Therapy 83 C. Health Risks of Overweight and Obesity 12 5. Pharmacotherapy 83 1. Morbidity 12 6. Surgery 86 2. Overweight/Obesity and Morbidity I. Smoking Cessation in the Overweight in Minority Populations 23 or Obese Patient 91 3. Obesity and Mortality 23 J. Role of Health Professionals in D. Weight Loss and Mortality 25 Weight Loss Therapy 92 E. Environment 26 F. Genetic Influence in the Development 5. Summary of Recommendations 95 of Overweight and Obesity 27 6. Future Research 98 3 Examination of Randomized Controlled A. Intervention Approaches 98 Trial Evidence 29 B. Causes and Mechanisms of A. Why Treat Overweight and Obesity? 29 Overweight and Obesity 99 1. Blood Pressure 29 C. Abdominal Fat, Body Weight and 2. Serum/Plasma Lipids and Disease Risk 99 Lipoproteins 33 D. Assessment Methods 99 3. Impaired Glucose Tolerance and Diabetes 39 7. Appendices 100 4. Decreases in Abdominal Fat with Appendix I.A.1 Guidelines Development Weight Loss 41 Methodology 100 B. What Treatments are Effective? 42 Appendix I.A.2 Literature Review 109 1. Dietary Therapy 42 Appendix II Description of Evidence 112 2. Physical Activity 44 Appendix III Special Populations 117 3. Combined Therapy 47 Appendix IV Obesity and Sleep Apnea 137 4. Behavior Therapy 48 Appendix V Body Mass Index Chart— 5. Pharmacotherapy 53 How to Measure Obesity 139 6. Surgery 54 Appendix VI Practical Dietary Therapy 7. Other Interventions for Overweight Information 141 and Obesity Treatment 55 Appendix VII Resource List 165 Appendix VIII Glossary of Terms 168 4. Treatment Guidelines 56 A. Overview 56 List of Abbreviations 179 B. Assessment and Classification of Reference List 181 Overweight and Obesity 56 1. Assessment of Overweight and Publication List 226 Obesity 56 vi
  8. 8. F OREWORD In 1995, the National Obesity Education members methodically and critically examined a Initiative of the National Heart, Lung, and vast amount of published scientific evidence. Blood Institute (NHLBI), in cooperation with The panel also obtained scientific input from the National Institute of Diabetes and Digestive approximately 115 outside reviewers. The result and Kidney Diseases (NIDDK), convened the was The Clinical Guidelines on the Identification, first Expert Panel on the Identification, Evaluation, and Treatment of Overweight and Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report. Dr. Obesity in Adults to develop clinical practice David Schriger of the University of California at guidelines for primary care practitioners. Los Angeles, who is a methodologist consultant in the area of evidence-based practice guidelines, The impetus for these guidelines was the recog- and Dr. Elaine Chiquette of the San Antonio nition that the prevalence of overweight and Cochrane Center in Texas, who developed the obesity in the United States is increasing, and evidence tables, served as key advisors to the that practitioners need to be alerted to the panel. accompanying health risks. According to the lat- est statistics from the third National Health and Evidence examined by the panel included: Nutrition Examination Survey, 97 million research on the relationship of overweight and Americans are overweight or obese. Excess obesity to high blood pressure, high blood cho- weight is often accompanied by high blood pres- lesterol, type 2 diabetes, stroke, congestive heart sure, high blood cholesterol, type 2 diabetes, failure, coronary heart disease, various cancers, coronary heart disease, and other health prob- osteoarthritis, and sleep apnea; risks associated lems. The total costs attributable to obesity-relat- with the distribution and amount of body fat; ed disease approach $100 billion annually in the and various treatment strategies, including diet, United States. physical activity, behavior therapy, pharma- cotherapy, and surgery. The resulting guidelines The panel used the principles of evidence-based document how different treatment strategies medicine, including an evidence model and evi- affect weight loss and how weight control affects dence categories. It was the first time a panel the major risk factors for heart disease and thoroughly examined the scientific evidence for stroke. risks associated with overweight and obesity, and their treatments, and developed clinical practice The guidelines have been reviewed and endorsed recommendations based on their conclusions. by many professional organizations. In fact, because of the associated risks between high The panel was headed by Dr. F. Xavier Pi- blood pressure and high blood cholesterol and Sunyer, of St. Luke’s/Roosevelt Hospital Center overweight and obesity, the document represents in New York City. He and the other 23 panel vii
  9. 9. the first clinical practice guidelines to be reviewed and endorsed by members of the coor- dinating committees of both the National Cholesterol Education Program and the National High Blood Pressure Education Program which comprise approximately 52 pro- fessional societies, government agencies, and consumer organizations. Two additional groups endorsing the guidelines are the North American Association for the Study of Obesity and the NIDDK National Task force on the Prevention and Treatment of Obesity. The report, the evidence model and its accom- panying evidence tables, and a body mass index calculator are available on the NHLBI website at the following location: http://www.nhlbi.nih. gov./nhlbi/cardio/obes/prof/guidelns/ob_home. htm An abbreviated version of the evidence report is being prepared and will be distributed to prima- ry care physicians, nurses, registered dietitians and nutritionists, and other health care practi- tioners. It is our hope that these clinical guidelines will not only help the health care practitioner under- stand the importance of weight management but also provide them with the tools to assess and treat their patients more effectively. Equally important, we hope that the guidelines lead to a greater public understanding of obesity and a greater appreciation for the persistent efforts of millions of people to lose weight. Claude Lenfant, M.D. Director National Heart, Lung, and Blood Institute viii
  10. 10. EVIDENCE REPORT ENDORSEMENTS NATIONAL CHOLESTEROL EDUCATION PROGRAM (NCEP) Coordinating Committee Member Organizations Theodore G. Ganiats, M.D., American Academy of Family Physicians, Gary Graham, M.D., American Academy of Insurance Medicine, Ronald Kleinman, M.D., American Academy of Pediatrics, Ann Smith, R.N., C.O.H.N.-S., American Association of Occupational Health Nurses, Richard C. Pasternak, M.D., F.A.C.C., American College of Cardiology, Gerald T. Gau, M.D., American College of Chest Physicians, Ruth Ann Jordan, M.D., American College of Occupational and Environmental Medicine, Thomas E. Nolan, M.D., American College of Obstetricians and Gynecologists, Alan J. Garber, M.D., Ph.D., American Diabetes Association, Inc., Linda Van Horn, Ph.D., R.D., American Dietetic Association, Scott Grundy, M.D., Ph.D., American Heart Association, Sandra Cornett, R.N., Ph.D., American Hospital Association, Yank D. Coble, Jr., M.D., American Medical Association, Joan Watson, R.N., Ph.D., F.A.A.N., American Nurses’ Association, Michael Clearfield, D.O., American Osteopathic Association, Joanne Mitten, M.H.E., Association of State and Territorial Health Officials, Gerald J. Wilson, M.B.A., Citizens for Public Action on Blood Pressure and Cholesterol, Inc., Linda Burnes-Bolton, Dr.P.H., R.N., National Black Nurses’ Association, Inc., Luther T. Clark, M.D., National Medical Association, Darlene Lansing, M.P.H., R.D., Society for Nutrition Education Associate Member Coordinating Committee Organizations Stanley Wallach, M.D., American College of Nutrition, Donald O. Fedder, Dr.P.H., M.P.H., Society for Public Health Education Federal Agency Liaison Coordinating Committee Representatives Yvonne L. Bronner, Sc.D., R.D., L.D., NHLBI Ad Hoc Committee on Minority Populations, Francis D. Chesley, M.D., Agency for Health Care Policy and Research, William H. Dietz, M.D., Ph.D., Centers for Disease Control and Prevention, Thomas M. Lasater, Ph.D., Coordinating Committee for the Community Demonstration Studies, Alanna Moshfegh, M.S., R.D., Department of Agriculture, Col. Michael Parkinson, M.D., M.P.H., Department of Defense, Pamela Steele, M.D., Department of Veterans Affairs, Celia Hayes, M.P.H., R.D., Health Resources and Services Administration, Clifford Johnson, M.P.H., National Center for Health Statistics, Linda Meyers, Ph.D., Office of Disease Prevention and Health Promotion NATIONAL HIGH BLOOD PRESSURE EDUCATION PROGRAM (NHBPEP) Coordinating Committee Member Organizations Lee A. Green, M.D., M.P.H., American Academy of Family Physicians, Jack P. Whisnant, M.D., American Academy of Neurology, Barry N. Hyman, M.D., F.A.C.P., American Academy of Ophthalmology, Lisa Mustone-Alexander, M.P.H., P.A., American Academy of Physician Assistants, Henry Guevara, B.S.N., R.N., C.O.H.N.-S., American Association of Occupational Health Nurses, Edward D. Frohlich, M.D., American College of Cardiology, Sheldon G. Sheps, M.D., American College of Chest Physicians, Ron Stout, M.D., American College of Occupational and Environmental Medicine, Jerome D. Cohen, M.D., American College of Physicians, Carlos Vallbona, M.D., American College of Preventive Medicine, James R. Sowers, M.D., American Diabetes Association, Inc., Mary C. Winston, Ed.D., R.D., American Dietetic Association, Daniel W. Jones, M.D., American Heart Association, Roxane Spitzer, Ph.D., F.A.A.N., American Hospital Association, Nancy Houston Miller, B.S.N., American Nurses’ Association, Linda Casser, O.D., American Optometric Association, William A. Nickey, D.O., American Osteopathic Association, Raymond W. Roberts, Pharm.D., American Pharmaceutical Association, Pamela J. Colman, D.P.M., American Podiatric Medical Association, Nancy McKelvey, M.S.N., R.N., American Red Cross, Barry L. Carter, Pharm.D., F.C.C.P., American Society of Health-System Pharmacists, Norman M. Kaplan, M.D., American Society of Hypertension, Jackson T. Wright, M.D., Ph.D., Association of Black Cardiologists, Gerald J. Wilson, M.B.A., Citizens for Public Action on Blood Pressure and Cholesterol, Inc., Joseph L. Izzo, Jr., M.D., Council on Geriatric Cardiology, James W. Reed, M.D., F.A.C.P., F.A.C.E., International Society on Hypertension in Blacks, Rita Strickland, Ed.D., R.N., National Black Nurses’ Association, Inc., William Manger, M.D., Ph.D., National Hypertension Association, Inc., Murray Epstein, M.D., National Kidney Foundation, Inc., Otelio S. Randall, M.D., F.A.C.C., National Medical Association, Edwin Marshall, O.D., M.P.H., National Optometric Association, Harold W. “Pete” Todd, National Stroke Association, Kathryn M. Kolasa, Ph.D., R.D., L.D.N., Society for Nutrition Education Federal Agency Liaison Coordinating Committee Representatives Keith Ferdinand, M.D., F.A.C.C., NHLBI Ad Hoc Committee on Minority Populations, Francis D. Chesley, M.D., Agency for Health Care Policy and Research, H. Mitchell Perry, Jr., M.D., Department of Veterans Affairs, Jay Merchant, M.H.A., Health Care Financing Administration, Vicki Burt, R.N., Sc.M., National Center for Health Statistics, Elizabeth H. Singer, M.S., National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) NIDDK NATIONAL TASK FORCE ON THE PREVENTION AND TREATMENT OF OBESITY NORTH AMERICAN ASSOCIATION FOR THE STUDY OF OBESITY (NAASO) ix
  11. 11. E XECUTIVE S UMMARY Introduction tural, physiological, metabolic and genetic factors. An estimated 97 million adults in the United While there is agreement about the health risks States are overweight or obese, a condition that of overweight and obesity, there is less agreement substantially raises their risk of morbidity from about their management. Some have argued hypertension, dyslipidemia, type 2 diabetes, against treating obesity because of the difficulty coronary heart disease, stroke, gallbladder dis- in maintaining long-term weight loss and of ease, osteoarthritis, sleep apnea and respiratory potentially negative consequences of the fre- problems, and endometrial, breast, prostate, and quently seen pattern of weight cycling in obese colon cancers. Higher body weights are also asso- subjects. Others argue that the potential hazards ciated with increases in all-cause mortality. Obese of treatment do not outweigh the known hazards individuals may also suffer from social stigmati- of being obese. The intent of these guidelines is zation and discrimination. As a major contributor to provide evidence for the effects of treatment to preventive death in the United States today, on overweight and obesity. The guidelines focus overweight and obesity pose a major public on the role of the primary care practitioner in health challenge. treating overweight and obesity. Overweight is here defined as a body mass index Evidence-Based Guidelines (BMI) of 25 to 29.9 kg/m2 and obesity as a BMI To evaluate published information and to deter- of ≥ 30 kg/m2. However, overweight and obesity mine the most appropriate treatment strategies are not mutually exclusive, since obese persons that would constitute evidence-based clinical are also overweight. A BMI of 30 is about 30 lb guidelines on overweight and obesity for physi- overweight and equivalent to 221 lb in a 6'0" cians and associated health professionals in clini- person and to 186 lb in one 5'6". The number cal practice, health care policy makers, and clini- of overweight and obese men and women has cal investigators, the National Heart, Lung, and risen since 1960; in the last decade the percent- Blood Institute’s Obesity Education Initiative in age of people in these categories has increased to cooperation with the National Institute of 54.9 percent of adults age 20 years or older. Diabetes and Digestive and Kidney Diseases con- Overweight and obesity are especially evident in vened the Expert Panel on the Identification, some minority groups, as well as in those with Evaluation, and Treatment of Overweight and lower incomes and less education. Obesity in Adults in May 1995. The guidelines Obesity is a complex multifactorial chronic dis- are based on a systematic review of the published ease that develops from an interaction of geno- scientific literature found in MEDLINE from type and the environment. Our understanding of January 1980 to September 1997 of topics iden- how and why obesity develops is incomplete, but tified by the panel as key to extrapolating the involves the integration of social, behavioral, cul- data related to the obesity evidence model. xi
  12. 12. Evidence from approximately 394 randomized summarizes the categories of evidence by their controlled trials (RCTs) was considered by the source and provides a definition for each category. panel. s Who is at Risk? All overweight and obese The panel is comprised of 24 members, 8 ex- adults (age 18 years of age or older) with a officio members, and a methodologist consul- BMI of ≥25 are considered at risk for devel- tant. Areas of expertise contributed to by panel oping associated morbidities or diseases such members included primary care, epidemiology, as hypertension, high blood cholesteral, type clinical nutrition, exercise physiology, psycholo- 2 diabetes, coronary heart disease, and other gy, physiology, and pulmonary disease. There diseases. Individuals with a BMI of 25 to were five meetings of the full panel and two 29.9 are considered overweight, while individ- additional meetings of the executive committee uals with a BMI ≥30 are considered obese. comprised of the panel chair and four panel Treatment of overweight is recommended members. only when patients have two or more risk fac- The San Antonio Cochrane Center assisted the tors or a high waist circumference. It should panel in the literature abstraction and in orga- focus on altering dietary and physical activity nizing the data into appropriate evidence tables. patterns to prevent development of obesity The center pretested and used a standardized and to produce moderate weight loss. 25-page form or “Critical Review Status Sheet” Treatment of obesity should focus on produc- for the literature abstraction. Ultimately, 236 ing substantial weight loss over a prolonged RCT articles were abstracted and the data were period. The presence of comorbidities in over- then compiled into individual evidence tables weight and obese patients should be consid- developed for each RCT. The data from these ered when deciding on treatment options. RCTs served as the basis for many of the recom- s Why Treat Overweight and Obesity? Obesity is mendations contained in the guidelines. clearly associated with increased morbidity The panel determined the criteria for deciding and mortality. There is strong evidence that on the appropriateness of an article. At a mini- weight loss in overweight and obese individu- mum, studies had to have a time frame from als reduces risk factors for diabetes and car- start to finish of at least 4 months. The only diovascular disease (CVD). Strong evidence exceptions were a few 3-month studies related to exists that weight loss reduces blood pressure dietary therapy and pharmacotherapy. To con- in both overweight hypertensive and nonhy- sider the question of long-term maintenance, pertensive individuals; reduces serum triglyc- studies with outcome data provided at approxi- erides and increases high-density lipoprotein mately 1 year or longer were examined. (HDL)-cholesterol; and generally produces Excluded were studies in which self-reported some reduction in total serum cholesterol and weights by subjects were the only indicators used low-density lipoprotein (LDL)-cholesterol. to measure weight loss. No exclusions of studies Weight loss reduces blood glucose levels in were made by study size. The panel weighed the overweight and obese persons without dia- evidence based on a thorough examination of betes; and weight loss also reduces blood glu- the threshold or magnitude of the treatment cose levels and HbA1c in some patients with effect. Each evidence statement (other than type 2 diabetes. Although there have been no those with no available evidence) and each rec- prospective trials to show changes in mortality ommendation is categorized by a level of evi- with weight loss in obese patients, reductions dence which ranges from A to D. Table ES-1 in risk factors would suggest that develop- xii
  13. 13. Table ES-1: E V I D E N C E C AT E G O R I E S Evidence Sources of Category Evidence Definition A Randomized Evidence is from endpoints of well-designed RCTs (or trials controlled trials that depart only minimally from randomization) that provide (rich body of a consistent pattern of findings in the population for which data) the recommendation is made. Category A therefore requires substantial numbers of studies involving substantial numbers of participants. B Randomized Evidence is from endpoints of intervention studies that controlled trials include only a limited number of RCTs, post hoc or subgroup (limited body analysis of RCTs, or meta-analysis of RCTs. In general, of data) Category B pertains when few randomized trials exist, they are small in size, and the trial results are somewhat inconsistent, or the trials were undertaken in a population that differs from the target population of the recommendation. C Nonrandomized Evidence is from outcomes of uncontrolled or nonrandomized trials trials or from observational studies. Observational studies D Panel Expert judgment is based on the panel’s synthesis of evidence Consensus from experimental research described in the literature and/or Judgment derived from the consensus of panel members based on clinical experience or knowledge that does not meet the above-listed criteria. This category is used only in cases where the provision of some guidance was deemed valuable but an adequately compelling clinical literature addressing the subject of the rec- ommendation was deemed insufficient to justify placement in one of the other categories (A through C). xiii
  14. 14. ment of type 2 diabetes and CVD would be s Body Mass Index. The BMI, which describes reduced with weight loss. relative weight for height, is significantly cor- related with total body fat content. The BMI s What Treatments Are Effective? A variety of should be used to assess overweight and obesi- effective options exist for the management of ty and to monitor changes in body weight. In overweight and obese patients, including addition, measurements of body weight alone dietary therapy approaches such as low-calorie can be used to determine efficacy of weight diets and lower-fat diets; altering physical loss therapy. BMI is calculated as weight activity patterns; behavior therapy techniques; (kg)/height squared (m2). To estimate BMI pharmacotherapy*; surgery; and combinations of these techniques. using pounds and inches, use: [weight (pounds)/height (inches)2] x 703. Weight clas- Clinical Guidelines sifications by BMI, selected for use in this Treatment of the overweight or obese patient is a report, are shown in Table ES-2. A conversion two-step process: assessment and treatment man- table of heights and weights resulting in agement. Assessment requires determination of selected BMI units is provided in Table ES-3. the degree of overweight and overall risk status. s Waist Circumference. The presence of excess Management includes both reducing excess body fat in the abdomen out of proportion to total weight and instituting other measures to control body fat is an independent predictor of risk accompanying risk factors. factors and morbidity. Waist circumference is Assessment: When assessing a patient for risk positively correlated with abdominal fat con- status and as a candidate for weight loss therapy, tent. It provides a clinically acceptable mea- consider the patient’s BMI, waist circumference, surement for assessing a patient's abdominal and overall risk status. Consideration also needs fat content before and during weight loss to be given to the patient’s motivation to lose treatment. The sex-specific cutoffs noted on weight. the next page can be used to identify TABLE ES-2: C L A S S I F I C AT I O N OF OVERWEIGHT AND OBESITY BY BMI Obesity Class BMI (kg/m2) Underweight < 18.5 Normal 18.5 – 24.9 Overweight 25.0 – 29.9 Obesity I 30.0 – 34.9 II 35.0 – 39.9 Extreme Obesity III ≥ 40 * As of September 1997, the Food and Drug Administration (FDA) requested the voluntary withdrawal from the market of dexfenfluramine and fenfluramine due to a reported association between valvular heart disease and the use of dexfenfluramine or fenfluramine alone or combined with phentermine. The use of these drugs for weight reduction, therefore, is not recommended in this report. Sibutramine is approved by FDA for long-term use. It has limited but definite effects on weight loss and can facilitate weight loss maintenance (Note: FDA approval for orlistat is pending a resolution of labeling issues and results of Phase III trials.) xiv
  15. 15. HIGH RISK mg/dL), low HDL-cholesterol (< 35 mg/dL), impaired fasting glucose (fasting plasma glu- cose of 110 to 125 mg/dL), family history of Men > 102 cm ( > 40 in) premature CHD (definite myocardial infarc- Women > 88 cm ( > 35 in) tion or sudden death at or before 55 years of age in father or other male first-degree rela- tive, or at or before 65 years of age in mother or other female first-degree relative), and age increased relative risk for the development of (men ≥ 45 years and women ≥ 55 years or obesity-associated risk factors in most adults postmenopausal). Patients can be classified as with a BMI of 25 to 34.9 kg/m2: being at high absolute risk if they have three These waist circumference cutpoints lose their of the aforementioned risk factors. Patients at incremental predictive power in patients with high absolute risk usually require clinical a BMI ≥ 35 kg/m2 because these patients will management of risk factors to reduce risk. exceed the cutpoints noted above. Table ES-4 Patients who are overweight or obese often adds the disease risk of increased abdominal have other cardiovascular risk factors. fat to the disease risk of BMI. These cate- Methods for estimating absolute risk status for gories denote relative risk, not absolute risk; developing cardiovascular disease based on that is, relative to risk at normal weight. They these risk factors are described in detail in the should not be equated with absolute risk, National Cholesterol Education Program’s which is determined by a summation of risk Second Report of the Expert Panel on the factors. They relate to the need to institute Detection, Evaluation, and Treatment of High weight loss therapy and do not directly define Blood Cholesterol in Adults (NCEP’s ATP II) the required intensity of modification of risk and the Sixth Report of the Joint National factors associated with obesity. Committee on Prevention, Detection, s Risk Status. Assessment of a patient’s absolute Evaluation, and Treatment of High Blood risk status requires examination for the pres- Pressure (JNC VI). The intensity of interven- ence of: tion for cholesterol disorders or hypertension is adjusted according to the absolute risk sta- Disease conditions: established coronary heart tus estimated from multiple risk correlates. disease (CHD), other atherosclerotic diseases, These include both the risk factors listed type 2 diabetes, and sleep apnea; patients with above and evidence of end-organ damage pre- these conditions are classified as being at very sent in hypertensive patients. Approaches to high risk for disease complications and mor- therapy for cholesterol disorders and hyper- tality. tension are described in ATP II and JNC VI, Other obesity-associated diseases: gynecologi- respectively. In overweight patients, control of cal abnormalities, osteoarthritis, gallstones cardiovascular risk factors deserves equal and their complications, and stress inconti- emphasis as weight reduction therapy. nence. Reduction of risk factors will reduce the risk Cardiovascular risk factors: cigarette smoking, for cardiovascular disease whether or not hypertension (systolic blood pressure ≥ 140 efforts at weight loss are successful. mm Hg or diastolic blood pressure ≥ 90 mm Other risk factors: physical inactivity and Hg, or the patient is taking antihypertensive high serum triglycerides (> 200 mg/dL). agents), high-risk LDL-cholesterol (≥ 160 When these factors are present, patients can xv
  16. 16. Table ES-3: S E L E C T E D BMI U N I T S C AT E G O R I Z E D BY INCHES (CM) AND POUNDS (KG) Body weight in pounds (kg) Height in inches (cm) BMI 25 kg/m 2 BMI 27 kg/m2 BMI 30 kg/m2 58 (147.32) 119 (53.98) 129 (58.51) 143 (64.86) 59 (149.86) 124 (56.25) 133 (60.33) 148 (67.13) 60 (152.40) 128 (58.06) 138 (62.60) 153 (69.40) 61 (154.94) 132 (59.87) 143 (64.86) 158 (71.67) 62 (157.48) 136 (61.69) 147 (66.68) 164 (74.39) 63(160.02) 141 (63.96) 152 (68.95) 169 (76.66) 64 (162.56) 145 (65.77) 157 (71.21) 174 (78.93) 65 (165.10) 150 (68.04) 162 (73.48) 180 (81.65) 66 (167.64) 155 (70.31) 167 (75.75) 186 (84.37) 67 (170.18) 159 (72.12) 172 (78.02) 191 (86.64) 68 (172.72) 164 (74.39) 177 (80.29) 197 (89.36) 69 (175.26) 169 (76.66) 182 (82.56) 203 (92.08) 70 (177.80) 174 (78.93) 188 (85.28) 207 (93.89) 71 (180.34) 179 (81.19) 193 (87.54) 215 (97.52) 72 (182.88) 184 (83.46) 199 (90.27) 221 (100.25) 73 (185.42) 189 (85.73) 204 (92.53) 227 (102.97) 74 (187.96) 194 (88.00) 210 (95.26) 233 (105.69) 75 (190.50) 200 (90.72) 216 (97.98) 240 (108.86) 76 (193.04) 205 (92.99) 221(100.25) 246 (111.58) Metric conversion formula = Non-metric conversion formula = weight (kg)/height (m) 2 [weight (pounds)/height (inches)2] x 703 Example of BMI calculation: Example of BMI calculation: A person who weighs 78.93 kilograms and is A person who weighs 164 pounds and is 177 centimeters tall has a BMI of 25: 68 inches (or 5' 8") tall has a BMI of 25: weight (78.93 kg)/height (1.77 m)2 = 25 [weight(164 pounds)/height (68 inches)2] x 703 = 25 xvi
  17. 17. be considered to have incremental absolute patient’s motivation for weight loss and pre- risk above that estimated from the preceding pare the patient for treatment. This can be risk factors. Quantitative risk contribution is done by enumerating the dangers accompany- not available for these risk factors, but their ing persistent obesity and by describing the presence heightens the need for weight reduc- strategy for clinically assisted weight reduc- tion in obese persons. tion. Reviewing the patients’ past attempts at weight loss and explaining how the new treat- s Patient Motivation. When assessing the ment plan will be different can encourage patient’s motivation to enter weight loss ther- patients and provide hope for successful apy, the following factors should be evaluated: weight loss. reasons and motivation for weight reduction; previous history of successful and unsuccess- Evaluation and Treatment: The general goals of ful weight loss attempts; family, friends, and weight loss and management are: (1) at a mini- work-site support; the patient’s understanding mum, to prevent further weight gain; (2) to of the causes of obesity and how obesity con- reduce body weight; and (3) to maintain a lower tributes to several diseases; attitude toward body weight over the long term. The overall physical activity; capacity to engage in physi- strategy for the evaluation and treatment of cal activity; time availability for weight loss overweight and obese patients is presented in the intervention; and financial considerations. In Treatment Algorithm on the next page. This addition to considering these issues, the algorithm applies only to the assessment for health care practitioner needs to heighten a overweight and obesity and subsequent decisions Table ES-4: C L A S S I F I C AT I O N OF OVERWEIGHT AND OBESITY BY B M I , WA I S T CIRCUMFERENCE A N D A S S O C I AT E D D I S E A S E R I S K * Disease Risk* Relative to Normal Weight and Waist Circumference Obesity Men ≤ 102 cm (≤ 40 in) > 102 cm (> 40 in) BMI (kg/m2) Class Women ≤ 88 cm (≤ 35 in) > 88 cm (> 35 in) Underweight <18.5 — — Normal+ 18.5 –24.9 — — Overweight 25.0 – 29.9 Increased High Obesity 30.0 – 34.9 I High Very High 35.0 – 39.9 II Very High Very High Extreme Obesity ≥40 III Extremely High Extremely High * Disease risk for type 2 diabetes, hypertension, and CVD. + Increased waist circumference can also be a marker for increased risk even in persons of normal weight. xvii
  18. 18. xviii Treatment Algorithm* 1 Patient Encounter 2 Hx of ≥ 25 BMI? No Yes 3 BMI measured in past 2 years? 4 6 BMI ≥ 30 OR • Measure weight, 5 BMI ≥ 25 OR 7 {[BMI 25 to 29.9 height, and waist waist circumference Yes Assess risk factors Yes OR waist circumference > 88 circumference > 88 cm (F) cm (F) > 102 cm (M)] 8 • Calculate BMI > 102 cm (M) AND ≥ 2 risk Clinician and patient factors} devise goals and No No treatment strategy for weight loss and risk factor control 14 12 Does Yes patient want to Yes Hx BMI ≥ 25? lose weight? 9 Progress Yes No No being made/goal 15 13 achieved? Brief reinforcement/ Advise to maintain educate on weight weight/address No management other risk factors 16 11 10 Periodic Weight Maintenance counseling: Assess reasons for Check • Dietary therapy failure to lose weight Examination • Behavior therapy • Physical activity Treatment * This algorithm applies only to the assessment for overweight and obesity and subsequent decisions based on that assessment. It does not include any initial overall assessment for cardiovascular risk factors or diseases that are indicated.
  19. 19. based on that assessment. It does not include s Strategies for Weight Loss and Weight any initial overall assessment for cardiovascular Maintenance. risk factors or diseases that are indicated. Dietary Therapy: A diet that is individually s Goals of Weight Loss and Management. planned and takes into account the patient’s overweight status in order to help create a The initial goal of weight loss therapy is to deficit of 500 to 1,000 kcal/day should be an reduce body weight by approximately 10 per- integral part of any weight loss program. A cent from baseline. If this goal is achieved, patient may choose a diet of 1,000 to 1,200 further weight loss can be attempted, if indi- kcal/day for women and 1,200 to 1,500 cated through further evaluation. kcal/day for men. Depending on the patient’s A reasonable time line for a 10 percent reduc- risk status, the low-calorie diet (LCD) recom- tion in body weight is 6 months of therapy. mended should be consistent with the For overweight patients with BMIs in the typ- NCEP’s Step I or Step II Diet (see page 74 of ical range of 27 to 35, a decrease of 300 to the guidelines). Besides decreasing saturated 500 kcal/day will result in weight losses of fat, total fats should be 30 percent or less of about 1⁄2 to 1 lb/week and a 10 percent loss in total calories. Reducing the percentage of 6 months. For more severely obese patients dietary fat alone will not produce weight loss with BMIs > 35, deficits of up to 500 to unless total calories are also reduced. 1,000 kcal/day will lead to weight losses of Isocaloric replacement of fat with carbohy- about 1 to 2 lb/week and a 10 percent weight drates will reduce the percentage of calories loss in 6 months. Weight loss at the rate of 1 from fat but will not cause weight loss. to 2 lb/week (calorie deficit of 500 to 1,000 Reducing dietary fat, along with reducing kcal/day) commonly occurs for up to 6 dietary carbohydrates, usually will be needed months. After 6 months, the rate of weight to produce the caloric deficit needed for an loss usually declines and weight plateaus acceptable weight loss. When fat intake is because of a lesser energy expenditure at the reduced, priority should be given to reducing lower weight. saturated fat to enhance lowering of LDL- Experience reveals that lost weight usually will cholesterol levels. Frequent contacts with the be regained unless a weight maintenance pro- practitioner during dietary therapy help to gram consisting of dietary therapy, physical promote weight loss and weight maintenance activity, and behavior therapy is continued at a lower weight. indefinitely. Physical Activity: An increase in physical After 6 months of weight loss treatment, activity is an important component of weight efforts to maintain weight loss should be put loss therapy, although it will not lead to sub- in place. If more weight loss is needed, anoth- stantially greater weight loss over 6 months. er attempt at weight reduction can be made. Most weight loss occurs because of decreased This will require further adjustment of the caloric intake. Sustained physical activity is diet and physical activity prescriptions. most helpful in the prevention of weight regain. In addition, it has a benefit in reduc- For patients unable to achieve significant ing cardiovascular and diabetes risks beyond weight reduction, prevention of further that produced by weight reduction alone. For weight gain is an important goal; such most obese patients, exercise should be initiat- patients may also need to participate in a ed slowly, and the intensity should be weight management program. xix
  20. 20. increased gradually. The exercise can be done sidering pharmacotherapy. all at one time or intermittently over the day. Pharmacotherapy: In carefully selected Initial activities may be walking or swimming patients, appropriate drugs can augment at a slow pace. The patient can start by walk- LCDs, physical activity, and behavior therapy ing 30 minutes for 3 days a week and can in weight loss. Weight loss drugs that have build to 45 minutes of more intense walking been approved by the FDA for long-term use at least 5 days a week. With this regimen, an can be useful adjuncts to dietary therapy and additional expenditure of 100 to 200 calories physical activity for some patients with a BMI per day can be achieved. All adults should set of ≥ 30 with no concomitant risk factors or a long-term goal to accumulate at least 30 diseases, and for patients with a BMI of ≥ 27 minutes or more of moderate-intensity physi- with concomitant risk factors or diseases. The cal activity on most, and preferably all, days risk factors and diseases considered important of the week. This regimen can be adapted to enough to warrant pharmacotherapy at a other forms of physical activity, but walking is BMI of 27 to 29.9 are hypertension, dyslipi- particularly attractive because of its safety and demia, CHD, type 2 diabetes, and sleep accessibility. Patients should be encouraged to apnea. Continual assessment by the physician increase “every day” activities such as taking of drug therapy for efficacy and safety is nec- the stairs instead of the elevator. With time, essary. depending on progress and functional capaci- ty, the patient may engage in more strenuous At the present time, sibutramine is available activities. Competitive sports, such as tennis for long-term use. (Note: FDA approval of and volleyball, can provide an enjoyable form orlistat is pending a resolution of labeling of exercise for many, but care must be taken issues and results of Phase III trials.) It to avoid injury. Reducing sedentary time is enhances weight loss modestly and can help another strategy to increase activity by under- facilitate weight loss maintenance. Potential taking frequent, less strenuous activities. side effects with drugs, nonetheless, must be kept in mind. With sibutramine, increases in Behavior Therapy: Strategies, based on learn- blood pressure and heart rate may occur. ing principles such as reinforcement, that pro- Sibutramine should not be used in patients vide tools for overcoming barriers to compli- with a history of hypertension, CHD, conges- ance with dietary therapy and/or increased tive heart failure, arrhythmias, or history of physical activity are helpful in achieving stroke. With orlistat, fat soluble vitamins may weight loss and weight maintenance. Specific require replacement because of partial malab- strategies include self-monitoring of both eat- sorption. All patients should be carefully ing habits and physical activity, stress manage- monitored for these side effects. ment, stimulus control, problem solving, con- tingency management, cognitive restructur- Weight Loss Surgery: Weight loss surgery is ing, and social support. one option for weight reduction in a limited number of patients with clinically severe obe- Combined Therapy: A combined intervention sity, i.e., BMIs ≥ 40 or ≥ 35 with comorbid of behavior therapy, an LCD, and increased conditions. Weight loss surgery should be physical activity provides the most successful reserved for patients in whom efforts at med- therapy for weight loss and weight mainte- ical therapy have failed and who are suffering nance. This type of intervention should be from the complications of extreme obesity. maintained for at least 6 months before con- xx
  21. 21. Gastrointestinal surgery (gastric restriction In the obese patient who smokes, smoking [vertical gastric banding] or gastric bypass cessation is a major goal of risk factor man- [Roux-en Y]) is an intervention weight loss agement. Many well-documented health ben- option for motivated subjects with acceptable efits accompany smoking cessation, but a operative risks. An integrated program must major obstacle to cessation has been the be in place to provide guidance on diet, phys- attendant weight gain observed in about 80 ical activity, and behavioral and social support percent of quitters. This weight gain averages both prior to and after the surgery. 4.5 to 7 lb, but in 13 percent of women and 10 percent of men, weight gain exceeds 28 lb. s Adapt Weight Loss Programs To Meet the Weight gain that accompanies smoking cessa- Needs of Diverse Patients. Standard treat- tion has been quite resistant to most dietary, ment approaches for overweight and obesity behavioral, or physical activity interventions. must be tailored to the needs of various patients or patient groups. Large individual The weight gained with smoking cessation is variation exists within any social or cultural less likely to produce negative health conse- group; furthermore, substantial overlap quences than would continued smoking. For among subcultures occurs within the larger this reason, smoking cessation should be society. There is, therefore, no “cookbook” or strongly advocated regardless of baseline standardized set of rules to optimize weight weight. Prevention of weight gain through reduction with a given type of patient. diet and physical activity should be stressed. However, to be more culturally sensitive and For practical reasons, it may be prudent to to incorporate patient characteristics in obesi- avoid initiating smoking cessation and weight ty treatment programs: consider and adapt loss therapy simultaneously. If weight gain the setting and staffing for the program; con- ensues after smoking cessation, it should be sider how the obesity treatment program inte- managed vigorously according to the guide- grates into other aspects of patient health care lines outlined in this report. Although short- and self care; and expect and allow for pro- term weight gain is a common side effect of gram modifications based on patient respons- smoking cessation, this gain does not rule out es and preferences. the possibility of long-term weight control. The issues of weight reduction after age 65 SUMMARY OF EVIDENCE-BASED RECOMMENDATIONS involve such questions as: does weight loss A A DVANTAGES OF W EIGHT L OSS reduce risk factors in older adults; are there risks associated with obesity treatment that The recommendation to treat overweight and are unique to older adults; and does weight obesity is based not only on evidence that relates reduction prolong the lives of older adults? obesity to increased mortality but also on RCT Although there is less certainty about the evidence that weight loss reduces risk factors for importance of treating overweight at older disease. Thus, weight loss may not only help ages than at younger ages, a clinical decision control diseases worsened by obesity, it may also to forgo obesity treatment in older adults help decrease the likelihood of developing these should be guided by an evaluation of the diseases. The panel reviewed RCT evidence to potential benefit of weight reduction and the determine the effect of weight loss on blood reduction of risk for future cardiovascular pressure and hypertension, serum/plasma lipid events. concentrations, and fasting blood glucose and fasting insulin. Recommendations focusing on xxi
  22. 22. these conditions underscore the advantages of inclusion in these guidelines, 14 RCT articles weight loss. examined lifestyle trials while the remaining 8 articles reviewed pharmacotherapy trials. There 1. Blood Pressure is strong evidence from the 14 lifestyle trials that To evaluate the effect of weight loss on blood weight loss produced by lifestyle modifications pressure and hypertension, 76 articles reporting in overweight individuals is accompanied by RCTs were considered for inclusion in these reductions in serum triglycerides and by increas- guidelines. Of the 45 accepted articles, 35 were es in HDL-cholesterol. Weight loss generally lifestyle trials and 10 were pharmacotherapy tri- produces some reductions in serum total choles- als. There is strong and consistent evidence from terol and LDL-cholesterol. Limited evidence these lifestyle trials in both overweight hyperten- exists that a decrease in abdominal fat correlates sive and nonhypertensive patients that weight with improvements in lipids, although the effect loss produced by lifestyle modifications reduces may not be independent of weight loss, and blood pressure levels. Limited evidence exists there is strong evidence that increased aerobic that decreases in abdominal fat will reduce blood activity to increase cardiorespiratory fitness pressure in overweight nonhypertensive individ- favorably affects blood lipids, particularly if uals, although not independent of weight loss, accompanied by weight loss. There is suggestive and there is considerable evidence that increased evidence from the eight randomized pharma- aerobic activity to increase cardiorespiratory fit- cotherapy trials that weight loss produced by ness reduces blood pressure (independent of weight loss medications and adjuvant lifestyle weight loss). There is also suggestive evidence modifications, including caloric restriction and from randomized trials that weight loss pro- physical activity, does not result in consistent duced by most weight loss medications, except effects on blood lipids. The following recom- for sibutramine, in combination with adjuvant mendation is based on the review of the data in lifestyle modifications will be accompanied by these 22 RCT articles: reductions in blood pressure. Based on a review of the evidence from the 45 RCT blood pressure articles, the panel makes the following recom- Weight loss is recommended to lower ele- mendation: vated levels of total cholesterol, LDL-cho- lesterol, and triglycerides, and to raise low levels of HDL-cholesterol in overweight Weight loss is recommended to lower ele- and obese persons with dyslipidemia. vated blood pressure in overweight and Evidence Category A. obese persons with high blood pressure. Evidence Category A. 3. Blood Glucose To evaluate the effect of weight loss on fasting 2. Serum/Plasma Lipids blood glucose and fasting insulin levels, 49 RCT Sixty-five RCT articles were evaluated for the articles were reviewed for inclusion in these effect of weight loss on serum/plasma concentra- guidelines. Of the 17 RCT articles accepted, 9 tions of total cholesterol, LDL-cholesterol, very RCT articles examined lifestyle therapy trials low-density lipoprotein (VLDL)-cholesterol, and 8 RCT articles considered the effects of triglycerides, and HDL-cholesterol. Studies were pharmacotherapy on weight loss and subsequent conducted on individuals over a range of obesity changes in blood glucose. There is strong evi- and lipid levels. Of the 22 articles accepted for dence from the nine lifestyle therapy trials that xxii
  23. 23. weight loss produced by lifestyle modification on nonrandomized studies as well as clinical reduces blood glucose levels in overweight and experience. obese persons without diabetes, and weight loss 1. BMI To Assess Overweight and Obesity reduces blood glucose levels and HbA lc in some There are a number of accurate methods to patients with type 2 diabetes. There is suggestive assess body fat (e.g., total body water, total body evidence that decreases in abdominal fat will potassium, bioelectrical impedance, and dual- improve glucose tolerance in overweight individ- energy X-ray absorptiometry), but no trial data uals with impaired glucose tolerance, although exist to indicate that one measure of fatness is not independent of weight loss; and there is lim- better than any other for following overweight ited evidence that increased cardiorespiratory fit- and obese patients during treatment. Since mea- ness improves glucose tolerance in overweight suring body fat by these techniques is often individuals with impaired glucose tolerance or expensive and is not readily available, a more diabetes, although not independent of weight practical approach for the clinical setting is the loss. In addition, there is suggestive evidence measurement of BMI; epidemiological and from randomized trials that weight loss induced observational studies have shown that BMI pro- by weight loss medications does not appear to vides an acceptable approximation of total body improve blood glucose levels any better than fat for the majority of patients. Because there are weight loss through lifestyle therapy in over- no published studies that compare the effective- weight persons both with and without type 2 ness of different measures for evaluating changes diabetes. Based on a full review of the data in in body fat during weight reduction, the panel these 17 RCT articles, the panel makes the fol- bases its recommendation on expert judgment lowing recommendation: from clinical experience: Weight loss is recommended to lower ele- Practitioners should use the BMI to assess vated blood glucose levels in overweight overweight and obesity. Body weight alone and obese persons with type 2 diabetes. can be used to follow weight loss, and to Evidence Category A. determine efficacy of therapy. Evidence Category C. B M EASUREMENT OF D EGREE OF 2. BMI To Estimate Relative Risk O VERWEIGHT AND O BESITY In epidemiological studies, BMI is the favored Patients should have their BMI and levels of measure of excess weight to estimate relative risk abdominal fat measured not only for the initial of disease. BMI correlates both with morbidity assessment of the degree of overweight and obe- and mortality; the relative risk for CVD risk fac- sity, but also as a guide to the efficacy of weight tors and CVD incidence increases in a graded loss treatment. Although there are no RCTs that fashion with increasing BMI in all population review measurements of overweight and obesity, groups. Moreover, calculating BMI is simple, the panel determined that this aspect of patient rapid, and inexpensive, and can be applied gen- care warranted further consideration and that erally to adults. The panel, therefore, makes this this guidance was deemed valuable. Therefore, recommendation: the following four recommendations that are included in the Treatment Guidelines were based xxiii
  24. 24. patient is very short, or has a BMI above the 25 to 34.9 range, waist cutpoints used for the gen- The BMI should be used to classify over- eral population may not be applicable. Based on weight and obesity and to estimate rela- the evidence from nonrandomized studies, the tive risk of disease compared to normal panel makes this recommendation: weight. Evidence Category C. For adult patients with a BMI of 25 to 3. Assessing Abdominal Fat 34.9 kg/m2, sex-specific waist circumference For the most effective technique for assessing cutoffs should be used in conjunction with abdominal fat content, the panel considered BMI to identify increased disease risks. measures of waist circumference, waist-to-hip Evidence Category C. ratio (WHR), magnetic resonance imaging (MRI), and computed tomography. Evidence from epidemiological studies shows waist cir- cumference to be a better marker of abdominal C G OALS FOR W EIGHT L OSS fat content than WHR, and that it is the most The general goals of weight loss and manage- practical anthropometric measurement for ment are to reduce body weight, to maintain a assessing a patient’s abdominal fat content before lower body weight over the long term, and to and during weight loss treatment. Computed prevent further weight gain. Evidence indicates tomography and MRI are both more accurate that a moderate weight loss can be maintained but impractical for routine clinical use. Based on over time if some form of therapy continues. It evidence that waist circumference is a better is better to maintain a moderate weight loss over marker than WHR—and taking into account a prolonged period than to regain from a that the MRI and computed tomography tech- marked weight loss. niques are expensive and not readily available for clinical practice—the panel makes the following 1. Initial Goal of Weight Loss from Baseline recommendation: There is strong and consistent evidence from randomized trials that overweight and obese patients in well-designed programs can achieve a The waist circumference should be used to weight loss of as much as 10 percent of baseline assess abdominal fat content. Evidence weight. In the diet trials, an average of 8 percent Category C. of baseline weight was lost. Since this average includes persons who did not lose weight, an individualized goal of 10 percent is reasonable. 4. Sex-Specific Measurements The panel, therefore, recommends that: Evidence from epidemiological studies indicates that a high waist circumference is associated with an increased risk for type 2 diabetes, dys- The initial goal of weight loss therapy lipidemia, hypertension, and CVD. Therefore, should be to reduce body weight by approx- the panel judged that sex-specific cutoffs for imately 10 percent from baseline. With waist circumference can be used to identify success, further weight loss can be attempt- increased risk associated with abdominal fat in ed if indicated through further assessment. adults with a BMI in the range of 25 to 34.9. Evidence Category A. These cutpoints can be applied to all adult eth- nic or racial groups. On the other hand, if a xxiv
  25. 25. 2. Amount of Weight Loss weight loss than lower-fat diets alone. Further, Randomized trials suggest that weight loss at the VLCDs produce greater initial weight losses rate of 1 to 2 lb/week (calorie deficit of 500 to than LCDs (over the long term of >1 year, 1,000 kcal/day) commonly occurs for up to 6 weight loss is not different than that of the months. LCDs). In addition, randomized trials suggest that no improvement in cardiorespiratory fitness as measured by VO2 max appears to occur in Weight loss should be about 1 to 2 lb/week obese adults who lose weight on LCDs alone for a period of 6 months, with the subse- without physical activity. The following recom- quent strategy based on the amount of mendations are based on the evidence extracted weight lost. Evidence Category B. from the 48 accepted articles: LCDs are recommended for weight loss in D H OW T O A CHIEVE W EIGHT L OSS overweight and obese persons. Evidence The panel reviewed relevant treatment strategies Category A. Reducing fat as part of an designed for weight loss that can also be used to LCD is a practical way to reduce calories. foster long-term weight control and prevention Evidence Category A. of weight gain. The consequent recommenda- tions emphasize the potential effectiveness of Reducing dietary fat alone without reduc- weight control using multiple interventions and ing calories is not sufficient for weight loss. strategies, including dietary therapy, physical However, reducing dietary fat, along with activity, behavior therapy, pharmacotherapy, and reducing dietary carbohydrates, can facili- surgery, as well as combinations of these strate- tate caloric reduction. Evidence Category A. gies. 1. Dietary Therapy A diet that is individually planned to help The panel reviewed 86 RCT articles to deter- create a deficit of 500 to 1,000 kcal/day mine the effectiveness of diets on weight loss should be an intregal part of any program (including LCDs, very low-calorie diets aimed at achieving a weight loss of 1 to 2 (VLCDs), vegetarian diets, American Heart lb/week. Evidence Category A. Association dietary guidelines, the NCEP’s Step I diet with caloric restriction, and other low-fat regimens with varying combinations of 2. Physical Activity macronutrients). Of the 86 articles reviewed, 48 Effects of Physical Activity on Weight Loss were accepted for inclusion in these guidelines. Twenty-three RCT articles were reviewed to These RCTs indicate strong and consistent evi- determine the effect of physical activity on dence that an average weight loss of 8 percent of weight loss, abdominal fat (measured by waist initial body weight can be obtained over 3 to 12 circumference), and changes in cardiorespiratory months with an LCD and that this weight loss fitness (VO2 max). Thirteen of these articles effects a decrease in abdominal fat; and, were accepted for inclusion in these guidelines. although lower-fat diets without targeted caloric A review of these articles reveals strong evidence reduction help promote weight loss by produc- that physical activity alone, i.e., aerobic exercise, ing a reduced caloric intake, lower-fat diets with in obese adults results in modest weight loss and targeted caloric reduction promote greater that physical activity in overweight and obese xxv
  26. 26. adults increases cardiorespiratory fitness, inde- physical activity produces greater weight loss pendent of weight loss. Randomized trials sug- than diet alone or physical activity alone, and gest that increased physical activity in over- that the combination of diet and physical activi- weight and obese adults reduces abdominal fat ty improves cardiorespiratory fitness as measured only modestly or not at all, and that regular by VO2 max in overweight and obese adults physical activity independently reduces the risk when compared to diet alone. The combined for CVD. The panel’s recommendation on phys- effect of a reduced calorie diet and increased- ical activity is based on the evidence from these physical activity seemingly produced modestly 13 articles: greater reductions in abdominal fat than either diet alone or physical activity alone, although it has not been shown to be independent of weight Physical activity is recommended as part of loss. The panel’s following recommendations are a comprehensive weight loss therapy and based on the evidence from these articles: weight control program because it: (1) modestly contributes to weight loss in over- weight and obese adults (Evidence The combination of a reduced calorie diet Category A), (2) may decrease abdominal and increased physical activity is recom- fat (Evidence Category B), (3) increases mended since it produces weight loss that cardiorespiratory fitness (Evidence Category may also result in decreases in abdominal A), and (4) may help with maintenance of fat and increases in cardiorespiratory fit- weight loss (Evidence Category C). ness. Evidence Category A. Physical activity should be an integral part of weight loss therapy and weight mainte- 3. Behavior Therapy nance. Initially, moderate levels of physical Thirty-six RCTs were reviewed to evaluate activity for 30 to 45 minutes, 3 to 5 days whether behavior therapy provides additional a week, should be encouraged. All adults benefit beyond other weight loss approaches, as should set a long-term goal to accumulate well as to compare various behavioral tech- at least 30 minutes or more of moderate- niques. Of the 36 RCTs reviewed, 22 were intensity physical activity on most, and accepted. These RCTs strongly indicate that preferably all, days of the week. Evidence behavioral strategies to reinforce changes in diet Category B. and physical activity in obese adults produce weight loss in the range of 10 percent over 4 months to 1 year. In addition, no one behavior therapy appeared superior to any other in its Effects of Physical Activity and Diet on Weight Loss (Combined Therapy) effect on weight loss; multimodal strategies Twenty-three RCT articles were reviewed to appear to work best and those interventions with determine the effects on body weight of a com- the greatest intensity appear to be associated bination of a reduced-calorie diet with increased with the greatest weight loss. Long-term follow- physical activity. Fifteen of these articles were up of patients undergoing behavior therapy accepted for inclusion in the guidelines. These shows a return to baseline weight for the great articles contain strong evidence that the combi- majority of subjects in the absence of continued nation of a reduced-calorie diet and increased behavioral intervention. Randomized trials sug- gest that behavior therapy, when used in combi- xxvi