Artificial sweetener that resists destruction by heat

Susan G. Dudek, RD, CDN, BS Nutrition Instructor, Dietetic Technology Program Erie Community College Williamsville, New York

Consultant Dietitian for Employee Assistance Program of Child and Family Services Williamsville, New York

S E V E N T H E D I T I O N

Nutrition Essentials for Nursing Practice

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Dudek, Susan G. Nutrition essentials for nursing practice / Susan G. Dudek. — 7th ed. p. ; cm. Includes bibliographical references and index. ISBN 978-1-4511-8612-3 (alk. paper) I. Title. [DNLM: 1. Diet Therapy—Handbooks. 2. Diet Therapy—Nurses’ Instruction. 3. Nutritional Physiological Phenomena — Handbooks. 4. Nutritional Physiological Phenomena—Nurses’ Instruction. WB 39] RM216 615.8'54—dc23

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Care has been taken to confi rm the accuracy of the information presented and to describe generally accepted practices. How- ever, the author, editors, and publisher are not responsible for errors or omissions or for any consequences from application of the information in this book and make no warranty, expressed or implied, with respect to the currency, completeness, or accuracy of the contents of the publication. Application of this information in a particular situation remains the professional responsibility of the practitioner; the clinical treatments described and recommended may not be considered absolute and universal recommendations.

The author, editors, and publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accordance with the current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant fl ow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any change in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new or infrequently employed drug.

Some drugs and medical devices presented in this publication have Food and Drug Administration (FDA) clearance for limited use in restricted research settings. It is the responsibility of the health care provider to ascertain the FDA status of each drug or device planned for use in his or her clinical practice.

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everyone should be so lucky to have a mom like her.

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iv

Reviewers

Zita Allen, RN, MSN Professor of Nursing Alverno College Milwaukee, Wisconsin

Carmen Bruni, MSN, RN, CAN Assistant Professor Texas A&M International University Laredo, Texas

Ann Cleary, DNS, RN, NP-C Associate Professor of Nursing Long Island University, Brooklyn Campus Brooklyn, New York

Tammie Cohen, RN, BS Nursing Instructor, Faculty Advisory Committee

Chairperson Western Suffolk BOCES Northport, New York

Janet Goeldner, MSN Professor University of Cincinnati—Raymond Walters College Cincinnati, Ohio

Coleen Kumar, RN, MSN Associate Professor Nursing Department Deputy Chairperson Kingsborough Community College Brooklyn, New York

Karen Lincoln, RNC, MSN Nursing Faculty Montcalm Community College Sidney, Michigan

Carol Isaac MacKusick, PhDc, MSN, RN, CNN Adjunct Faculty Clayton State University Morrow, Georgia

Marina Martinez-Kratz, RN, BSN, MS Professor of Nursing Jackson Community College Jackson, Michigan

Janet Tompkins McMahon, RN, MSN Clinical Associate Professor of Nursing Towson University Towson, Maryland

Patricia J. Neafsey, RD, PhD Professor University of Connecticut School of Nursing Storrs, Connecticut

Cheryl L. Neudauer, PhD, MEd Biology Faculty Center for Teaching and Learning Campus Leader Minneapolis Community and Technical College Minneapolis, Minnesota

Christine M. Prince, RN, BSN, CCM Nursing Faculty Brown Mackie College Indianapolis Indianapolis, Indiana

Rhonda Savain, RN, MSN Nursing Instructor Ready to Pass Inc. West Hempstead, New York

Nancy West, RN, MN Professor of Nursing Johnson County Community College Overland Park, Kansas

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v

L ike air and sleep, nutrition is a basic human need essential for survival. Nutrition provides energy and vitality, helps reduce the risk of chronic disease, and can aid in recovery. It is a dynamic blend of science and art, evolving over time and in response to technological advances and cultural shifts. Nutrition at its most basic level is food—for the mind, body, and soul.

Although considered the realm of the dietitian, nutrition is a vital and integral compo- nent of nursing care. Today’s nurses need to know, understand, apply, analyze, synthesize, and evaluate nutrition throughout the life cycle and along the wellness/illness continuum. They incorporate nutrition into all aspects of nursing care plans, from assessment and nursing diagnoses to implementation and evaluation. By virtue of their close contact with patients and families, nurses are often on the front line in facilitating nutrition. This text seeks to give student nurses a practical and valuable nutrition foundation to better serve themselves and their clients.

NEW TO THIS EDITION

This seventh edition continues the approach of providing the essential information nurses need to know for practice. Building upon this framework, content has been thoroughly updated to refl ect the latest evidence-based practice. Examples of content updates that are new to this edition are as follows:

■ MyPlate, which replaces MyPyramid as the graphic to illustrate the Dietary Guidelines for Americans

■ Recommended Dietary Allowances (RDAs) for calcium and vitamin D ■ Inclusion of a validated stand-alone nutrition screening tool for older adults that is ap-

propriate for community settings and in clinical practice ■ Expanded coverage of bariatric surgery and obesity in general, particularly with regard

to the importance of behavioral strategies for navigating our increasingly obesogenic environment

■ The low-FODMAP (fermental oligo-, di-, and monosaccharides and polyols) diet for irritable bowel syndrome and possibly other gastrointestinal disorders

■ A shift in focus from single nutrients (e.g., saturated fat) to a food pattern approach (e.g., the DASH diet) for communicating and implementing a heart healthy diet

■ Updated 2011 nutrition therapy guidelines for patients with chronic kidney disease who are not on dialysis

ORGANIZATION OF THE TEXT

Unit One is devoted to Principles of Nutrition. It begins with Chapter 1, Nutrition in Nursing, which focuses on why and how nutrition is important to nurses in all settings. Chapters devoted to carbohydrates, protein, lipids, vitamins, water and minerals, and energy balance provide a foundation for wellness. The second part of each chapter highlights health promotion topics and demonstrates practical application of essential information, such as how to increase fi ber intake, criteria to consider when buying a vitamin supplement, and the risks and benefi ts of a vegetarian diet.

Preface

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vi P R E F A C E

Unit Two, Nutrition in Health Promotion, begins with Chapter 8, Guidelines for Healthy Eating. This chapter features the Dietary Reference Intakes, the Dietary Guide- lines for Americans, and MyPlate. Other chapters in this unit examine consumer issues and cultural and religious infl uences on food and nutrition. The nutritional needs associated with the life cycle are presented in chapters devoted to pregnant and lactating women, chil- dren and adolescents, and older adults.

Unit Three, Nutrition in Clinical Practice, includes nutrition therapy for obesity and eating disorders, enteral and parenteral nutrition, metabolic and respiratory stress, gastro- intestinal disorders, diabetes, cardiovascular disorders, renal disorders, cancer, and HIV/ AIDS. Pathophysiology is tightly focused as it pertains to nutrition.

RECURRING FEATURES

This edition retains popular features of the previous edition to facilitate learning and engage students.

■ Check Your Knowledge presents true/false questions at the beginning of each chapter to assess the students’ baseline knowledge. Questions relate to chapter Learning Objectives.

■ Key Terms are defined in the margin for convenient reference. ■ Quick Bites—fewer and more condensed to improve layout and readability in the new

edition—provide quick nutrition facts, valuable information, and current research. ■ Nursing Process tables clearly present sample application of nutrition concepts in con-

text of the nursing process. ■ How Do You Respond? helps students identify potential questions they may encounter

in the clinical setting and prepares them to think on their feet. ■ A Case Study and Study Questions at the end of each chapter challenge students to

apply what they have learned. ■ Key Concepts summarize important information from each chapter.

TEACHING AND LEARNING RESOURCES

Instructors and students will fi nd valuable resources to accompany the book on at http://thePoint.lww.com/Dudek7e.

Resources for Instructors Comprehensive teaching resources are available to instructors upon adoption of this text and include the following materials.

■ A free E-book on thePoint provides access to the book’s full text and images online. ■ A Test Generator lets instructors put together exclusive new tests from a bank contain-

ing NCLEX-style questions. ■ PowerPoint Presentations provide an easy way to integrate the textbook with the class-

room. Multiple-choice and true/false questions are included to promote class participation. ■ An Image Bank provides the photographs and illustrations from this text for use in

course materials. ■ Access to all student resources is also provided.

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P R E F A C E vii

Resources for Students Students can activate the code in the front of this book at http://thePoint.lww.com/ activate to access the following free resources.

■ A free E-book on thePoint provides access to the book’s full text and images online. ■ NEW! Practice & Learn Interactive Case Studies provide realistic case examples and

offer students the opportunity to apply nutrition essentials to nursing care. ■ Journal Articles provided for each chapter offer access to current research available in

Lippincott Williams & Wilkins journals.

I hope this text and teaching/learning resource package provide the impetus to embrace nutrition on both a personal and professional level.

Susan G. Dudek, RD, CDN, BS

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viii

I am humbled and grateful to be still writing this book after six editions. It is a project that has been professionally rewarding, personally challenging, and rich with opportunities to grow. In large part, the success of this book rests with the dedicated and creative profes- sionals at Lippincott Williams & Wilkins. Because of their support and talents, I am able to do what I love—write, create, teach, and learn. I especially thank

■ David Troy, Senior Acquisitions Editor, who provided the spark to ignite the project. ■ Maria McAvey, Editorial Product Manager, for her meticulous attention to detail and

gentle guidance. ■ Marian Bellus, Production Project Manager; Holly Reid McLaughlin, Design Coordinator;

John Johnson, Education Marketing Manager, Nursing; and Latisha Ogelsby, Editorial Assistant, the behind-the-scene professionals whose efforts help transform an ugly duck- ling into a beautiful swan.

■ The reviewers of the sixth edition, whose insightful comments and suggestions helped shape a new and improved edition.

■ My friends and family—my sideline cheerleaders—who so patiently gave me the time and space to work on “my story.”

■ I am especially thankful to my husband Joe . . . always there through thick and thin.

Acknowledgments

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ix

U N I T O N E Principles of Nutrition 1

CHAPTER 1 Nutrition in Nursing 2 CHAPTER 2 Carbohydrates 18 CHAPTER 3 Protein 46 CHAPTER 4 Lipids 66 CHAPTER 5 Vitamins 92 CHAPTER 6 Water and Minerals 124 CHAPTER 7 Energy Balance 156

U N I T T W O Nutrition in Health Promotion 177

CHAPTER 8 Guidelines for Healthy Eating 178 CHAPTER 9 Consumer Issues 200 CHAPTER 10 Cultural and Religious Infl uences on Food and Nutrition 230 CHAPTER 11 Healthy Eating for Healthy Babies 257 CHAPTER 12 Nutrition for Infants, Children, and Adolescents 286 CHAPTER 13 Nutrition for Older Adults 320

U N I T T H R E E Nutrition in Clinical Practice 353

CHAPTER 14 Obesity and Eating Disorders 354 CHAPTER 15 Feeding Patients: Oral Diets and Enteral and Parenteral Nutrition 393 CHAPTER 16 Nutrition for Patients with Metabolic or Respiratory Stress 423 CHAPTER 17 Nutrition for Patients with Upper Gastrointestinal Disorders 443 CHAPTER 18 Nutrition for Patients with Disorders of the Lower GI Tract and

Accessory Organs 461 CHAPTER 19 Nutrition for Patients with Diabetes Mellitus 497 CHAPTER 20 Nutrition for Patients with Cardiovascular Disorders 535 CHAPTER 21 Nutrition for Patients with Kidney Disorders 567 CHAPTER 22 Nutrition for Patients with Cancer or HIV/AIDS 593

A P P E N D I C E S

APPENDIX 1 Dietary Reference Intakes (DRIs): Recommended Dietary Allowances and Adequate Intakes, Total Water and Macronutrients 624

APPENDIX 2 Dietary Reference Intakes (DRIs): Recommended Dietary Allowances and Adequate Intakes, Vitamins 625

APPENDIX 3 Dietary Reference Intakes (DRIs): Recommended Dietary Allowances and Adequate Intakes, Elements 628

APPENDIX 4 Answers to Study Questions 630

INDEX 633

Contents

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U N I T O N E

Principles of Nutrition

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2

C H E C K Y O U R K N O W L E D G E

Nutrition in Nursing1 TRUE FALSE

1 The nurse’s role in nutrition is to call the dietitian.

2 Nutrition screening is used to identify clients at risk for malnutrition.

3 The Joint Commission stipulates the criteria to be included on a nutritional screen for hospitalized patients.

4 Changes in weight refl ect acute changes in nutritional status.

5 A person can be malnourished without being underweight.

6 The only cause of a low serum albumin concentration is protein malnutrition.

7 “Signifi cant” weight loss is 5% of body weight in 1 month.

8 People who take fi ve or more prescription or over-the-counter medications or dietary supplements are at risk for nutritional problems.

9 Obtaining reliable and accurate information on what the client usually eats can help identify intake as a source of nutrition problems.

10 Physical signs and symptoms of malnutrition develop only after other signs of malnutri- tion are apparent (e.g., abnormal lab values, weight change).

U p o n c o m p l e t i o n o f t h i s c h a p t e r, y o u w i l l b e a b l e t o

1 Compare nutrition screening to nutrition assessment. 2 Evaluate weight loss for its signifi cance over a 1-month or 6-month interval. 3 Discuss the validity and reliability of using physical signs to support a nutritional diagnosis

of malnutrition. 4 Give examples of nursing diagnoses that may use nutrition therapy as an intervention. 5 Demonstrate how nurses can facilitate client and family teaching of nutrition therapy. 6 Explain why an alternative term to “diet” is useful.

L E A R N I N G O B J E C T I V E S

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C H A P T E R 1 Nutrition in Nursing 3

Based on Maslow’s hierarchy of needs, food and nutrition rank on the same level as air in the basic necessities of life. Obviously, death eventually occurs without food. But unlike air, food does so much more than simply sustain life. Food is loaded with personal, social, and cultural meanings that defi ne our food values, beliefs, and customs. That food nour- ishes the mind as well as the body broadens nutrition to an art as well as a science. Nutrition is not simply a matter of food or no food but rather a question of what kind, how much, how often, and why. Merging want with need and pleasure with health are keys to feeding the body, mind, and soul.

Although the dietitian is the nutrition and food expert, nurses play a vital role in nutri- tion care. Nurses may be responsible for screening hospitalized patients to identify patients at nutritional risk. They often serve as the liaison between the dietitian and physician as well as with other members of the health-care team. Nurses have far more contact with the patient and family and are often available as a nutrition resource when dietitians are not, such as during the evening, on weekends, and during discharge instructions. In home care and wellness settings, dietitians may be available only on a consultative basis. Nurses may reinforce nutrition counseling provided by the dietitian and may be responsible for basic nutrition education in hospitalized clients with low to mild nutritional risk. Nurses are inti- mately involved in all aspects of nutritional care.

This chapter discusses nutrition within the context of nursing, including nutrition screening and how nutrition can be integrated into the nursing care process.

NUTRITION SCREENING

Nutrition screening is a quick look at a few variables to identify individuals who are mal- nourished or who are at risk for malnutrition so that an in-depth nutrition assessment can follow. Screening tools should be simple, reliable, valid, applicable to most patients or clients in the group, and use data that is readily available (Academy of Nutrition and Dietetics, 2012). For instance, a community-based senior center may use a nutrition screen that focuses mostly on intake risks common to that population, such as whether the client eats alone most of the time and/or has physical limitations that impair the abil- ity to buy or cook food (Fig. 1.1). In contrast, common screening parameters in acute care settings include unintentional weight loss, appetite, body mass index (BMI), and disease severity. Advanced age, dementia, and other factors may be considered. There is no universally agreed upon tool that is valid and reliable at identifying risk of malnutrition in all populations at all times.

The Joint Commission, a nonprofi t organization that sets health-care standards and accredits health-care facilities that meet those standards, specifi es that nutrition screening be conducted within 24 hours after admission to a hospital or other health-care facility—even on weekends and holidays. The Joint Commission allows facilities to determine screening criteria and how risk is defi ned. For instance, a hospital may use serum creatinine level as a screening criterion, with a level greater than 2.5 mg/dL defi ned as “high risk” because the majority of their patients are elderly and the prevalence of chronic renal problems is high. The Joint Commission also leaves the decision of who performs the screening up to indi- vidual facilities. Because the standard applies 24 hours a day, 7 days a week, staff nurses are often responsible for completing the screen as part of the admission process. Clients who “pass” the initial screen are rescreened after a specifi ed amount of time to determine if their status has changed.

Nutritional Screen: a quick look at a few variables to judge a client’s relative risk for nutritional problems. Can be custom de- signed for a particular population (e.g., preg- nant women) or for a specific disorder (e.g., cardiac disease). Malnutrition: literally “bad nutrition” or any nutritional imbalance including overnutrition. In practice, malnutrition usually means undernu- trition or an inadequate intake of protein and/or calories that causes loss of fat stores and/or muscle wasting.

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4 U N I T 1 Principles of Nutrition

NUTRITION CARE PROCESS

Clients considered to be at moderate or high risk for malnutrition through screening are usually referred to a dietitian for a comprehensive nutritional assessment to identify spe- cifi c risks or confi rm the existence of malnutrition. Nutritional assessment is more accu- rately called the nutrition care process, which includes four steps (Fig. 1.2). While nurses use the same problem-solving model to develop nursing or multidisciplinary care plans that

I have an illness or condition that made me change the kind and/or amount of food I eat.

I eat fewer than two meals per day.

I eat few fruits or vegetables, or milk products.

I have three or more drinks of beer, liquor or wine almost every day.

I have tooth or mouth problems that make it hard for me to eat.

I don't always have enough money to buy the food I need.

I eat alone most of the time.

I take three or more different prescribed or over-the-counter drugs a day.

Without wanting to, I have lost or gained 10 pounds in the last six months.

I am not always physically able to shop, cook and/or feed myself.

TOTAL

YES

2

3

2

2

2

4

1

1

2

2

Total your nutritional score. If it’s –

Remember that warning signs suggest risk, but do not represent diagnosis of any condition.

Good! Recheck your nutritional score in six months.

You are at moderate nutritional risk. See what can be done to improve your eating habits and lifestyle. Your office on aging, senior nutrition program, senior citizens center or health department can help. Recheck your nutritional score in three months.

You are at high nutritional risk. Bring this checklist the next time you see your doctor, dietitian or other qualified health or social service professional. Talk with them about any problems you may have. Ask for help to improve your nutritional health.

0-2

3-5

6 or more

DETERMINE YOUR NUTRITIONAL HEALTH

The warning signs of poor nutritional health are often overlooked. Use this checklist to find out if you or someone you know is at nutritional risk.

Read the statements below. Circle the number in the “yes” column for those that apply to you or someone you know. For each “yes” answer, score the number in the box. Total your nutritional score.

■ F I G U R E 1 . 1 Determine your nutritional health. American Academy of Family Physicians, the American Dietetic Association, the National Council on the Aging, Inc. The Nutrition Screening Initiative.

Nutritional Assessment: an in-depth analysis of a person’s nutritional status. In the clinical setting, nutritional assessments focus on moderate- to high-risk patients with suspected or confirmed protein– energy malnutrition.

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C H A P T E R 1 Nutrition in Nursing 5

may also integrate nutrition, the nutritional plan of care devised by dietitians is specifi c for nutrition problems. Some obvious differences in focus are described below:

■ Dietitians may obtain much of their preliminary information about the patient from the nursing history and physical examination, such as height and weight; skin integrity; usual diet prior to admission; difficulty chewing, swallowing, or self-feeding; chief com- plaint; medications, supplements, and over-the-counter drugs used prior to admission; and living situation. Dietitians may request laboratory tests to assess vitamin levels when micronutrient deficiencies are suspected.

■ Dietitians interview patients and/or families to obtain a nutrition history, which may include information on current dietary habits; recent changes in intake or appetite; intake of snacks; alcohol consumption; food allergies and intolerances; ethnic, cultural, or religious diet influ- ences; nutrition knowledge and beliefs; and use of supplements. A nutrition history can help differentiate nutrition problems caused by inadequate intake from those caused by disease.

■ Dietitians usually calculate estimated calorie and protein requirements based on the assessment data and determine whether the diet ordered is adequate and appropriate for the individual.

■ Dietitians determine nutrition diagnoses that define the nutritional problem, etiology, and signs and symptoms. While a nursing diagnosis statement may begin with “Altered nutrition: eating less than the body needs,” a nutrition diagnosis would be more specific, such as “Inadequate protein–energy intake.”

■ Dietitians may also determine the appropriate malnutrition diagnosis code for the patient for hospital reimbursement purposes.

■ Nutrition interventions may include requesting a diet order change, requesting additional laboratory tests to monitor nutritional repletion, and performing nutrition counseling or education.

Screening

Nutrition assessment

Nutrition diagnosis

Nutrition intervention

Nutrition monitoring and evaluation

■ F I G U R E 1 . 2 The nutrition care process. Like the nursing process, the nutrition care process is a problem-solving method used to evaluate and treat nutrition-related problems.

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6 U N I T 1 Principles of Nutrition

NUTRITION IN THE NURSING PROCESS

In nursing care plans, nutrition may be part of the assessment data, diagnosis, plan, implementation, or evaluation. The remainder of this chapter is intended to help nurses provide quality nursing care that includes basic nutrition, not to help nurses become dietitians.

Assessment It is well recognized that malnutrition is a major contributor to morbidity, mortality, im- paired quality of life, and prolonged hospital stays (White et al., 2012). However, there is currently no single, universally agreed upon method to assess or diagnose malnutrition. Approaches vary widely and may lack sensitivity (the ability to diagnose all people who are malnourished) and specifi city (misdiagnosing a well-nourished person). For instance, albumin and prealbumin have been used as diagnostic markers of malnutrition. These pro- teins are now known to be negative acute phase proteins, which means their levels de- crease in response to infl ammation and physiologic stress. Because they are not specifi c for nutritional status, failure of these levels to increase with nutrition repletion does not mean that nutrition therapy is inadequate (Fessler, 2008). Although their usefulness in diagnosing malnutrition is limited, these proteins may help identify patients at high risk for morbidity, mortality, and malnutrition (Banh, 2006). BMI and some or all of the compo- nents of a subjective global assessment (Box 1.1) are commonly used to assess nutrition (Fessler, 2008).

Medical History and Diagnosis

The chief complaint and medical history may reveal disease-related risks for malnutrition and whether infl ammation is present (Fig. 1.3). Patients with gastrointestinal symptoms or disorders are among those who are most prone to malnutrition, particularly when symptoms such as nausea, vomiting, diarrhea, and anorexia last for more than 2 weeks. Box 1.2 lists psychosocial factors that may impact intake or requirements and help identify nutrition counseling needs.

Subjective Global Assessment (SGA): a clinical method of assessing nutritional status based on findings in a health history and physical examination.

Weight Change ■ Unintentional weight loss and the time

period of loss

Dietary Intake ■ Change from normal, duration, type of

diet consumed

Gastrointestinal Symptoms Lasting Longer than 2 Weeks ■ Nausea, vomiting, diarrhea, anorexia

Functional Capacity ■ Normal or suboptimal; ambulatory or

bedridden

Disease and Its Relation to Nutritional Requirements ■ Primary diagnosis; severity of metabolic

stress

Physical Signs and Severity of Findings ■ Loss of subcutaneous fat (triceps, chest),

muscle wasting (quadriceps, deltoids), ankle edema, sacral edema, ascites

CRITERIA INCLUDED IN SUBJECTIVE GLOBAL ASSESSMENTBox 1.1

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C H A P T E R 1 Nutrition in Nursing 7

Psychological Factors ■ Depression ■ Eating disorders ■ Psychosis

Social Factors ■ Illiteracy ■ Language barriers ■ Limited knowledge of nutrition and food

safety ■ Altered or impaired intake related to

culture ■ Altered or impaired intake related to

religion

■ Lack of caregiver or social support system

■ Social isolation ■ Lack of or inadequate cooking

arrangements ■ Limited or low income ■ Limited access to transportation to

obtain food ■ Advanced age (older than 80 years) ■ Lack of or extreme physical activity ■ Use of tobacco or recreational drugs ■ Limited use or knowledge of community

resources

PSYCHOSOCIAL FACTORS THAT MAY INFLUENCE INTAKE, NUTRITIONAL REQUIREMENTS, OR NUTRITION COUNSELINGBox 1.2

Acute illness (e.g., infection,

trauma, pancreatitis)

Inflammation/ catabolism

Frequent infection, altered GI function

Malnutrition

Inadequate intake/ nutrient availability

(anorexia, malabsorption)

Chronic illness (e.g., cancer, AIDS, COPD)

■ F I G U R E 1 . 3 Factors that may be involved in the etiology of illness-related malnutrition.

Body Mass Index

Body mass index (BMI) is an index of a person’s weight in relation to height used to estimate relative risk of health problems related to weight. Because it is relatively quick and easy to measure height and weight and requires little skill, actual measures, not estimates, should be used whenever possible to ensure accuracy and reliability. A patient’s stated height and weight should be used only when there are no other options.

Body Mass Index: an index of weight in relation to height that is calculated mathemat- ically by dividing weight in kilograms by the square of height in meters.

Q U I C K B I T E

Interpreting BMI

�18.5 underweight 18.5–24.9 healthy weight 25–29.9 overweight 30–34.9 obesity class 1 35–39.9 obesity class 2 �40 obesity class 3

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8 U N I T 1 Principles of Nutrition

“Healthy” or “normal” BMI is defi ned numerically as 18.5 to 24.9. Values above and below this range are associated with increased health risks. Although BMI can be calcu- lated with a mathematical formula, tables and nomograms are available for convenience (see Chapter 14). One drawback of using BMI is that a person can have a high BMI and still be undernourished in one or more nutrients if intake is unbalanced or if nutritional needs are high and intake is inadequate.

Weight Change

Unintentional weight loss is a well-validated indicator of malnutrition (White et al., 2012). The signifi cance of weight change is evaluated after the percentage of usual body weight lost in a given period of time is calculated (Box 1.3). Usually, weight changes are more refl ective of chronic, not acute, changes in nutritional status. The patient’s weight can be unreliable or invalid due to hydration status. Edema, anasarca, fl uid resuscitation, heart failure, and chronic liver or renal disease can falsely infl ate weight.

Dietary Intake

A decrease in intake compared to the patient’s normal intake may indicate nutritional risk. However, like other data, validity and reliability may be an issue. Although the nurse may only be required to fi ll in a blank space next to the word “appetite,” simply ask- ing the client “How is your appetite?” will probably not provide suffi cient information. A better question may be “Has the type or amount of food you eat recently changed? If so, please explain.” Consuming only liquids and severely limiting the type or amount of food are risks.

Another question to avoid while obtaining a nursing history is “Are you on a diet?” To many people, diet is synonymous with weight loss diet; they may fail to mention they use nutrition therapy to avoid sodium, modify fat, or count carbohydrates. A better question would be, “Do you avoid any particular foods?” or “Do you watch what you eat in any way?” Even the term “meal” may elicit a stereotypical mental picture. Questions to consider when asking a client about his or her usual intake appear in Box 1.4.