Obesity: An Overview of Assessment and Treatment
Lora E. Burke
Patricia K. Tuite
Melanie Warziski Turk
Obesity is a multifactorial disease involving complex interactions among genetic, metabolic, environmental, cultural, and psychosocial factors. Estimates from the 2003-2004 National Health and Nutrition Examination Survey (NHANES) indicate that 66.3% of the U.S. population is either overweight (body mass index [BMI] 25 to 29.9 kg/m2) or obese (BMI ≥ 30 kg/m2),1 with significant increases in the overweight prevalence among children and adolescents, and obesity prevalence in men between 1999 and 2004.2 In the United States today, obesity has become a pandemic, the most common nutritional problem, the second most preventable cause of death, a significant contributor to increased health care costs, and a condition that lessens life expectancy and reduces quality of life across the lifespan.3 This medical condition is not limited to the United States, and the World Health Organization (WHO) has now deemed overnutrition to be a health concern.4 Nearly 2.3 billion adults will be overweight and more than 700 million will be obese by 2015 according to estimates by the WHO. Despite overweight and obesity once being regarded as a problem of affluent countries, the prevalence of these conditions is on the increase in low- and middle-income countries, especially in metropolitan areas.5 See Figure 38-1 for the estimated prevalence of obesity in several countries.
Obesity has been linked to a host of chronic disorders associated with heart disease, including type 2 diabetes, dyslipidemia, and hypertension.6 It is associated with deleterious effects on the heart and circulatory system, contributing to an increased risk of arrhythmia, sudden death, congestive heart failure, and ischemic heart disease.7,8 Moreover, several physiologic parameters that affect cardiovascular risk factors are associated with obesity, such as lipoprotein oxidizability, arterial blood pressure, hemostatic or fibrinolytic abnormalities, and C-reactive protein, a vascular inflammatory marker.9,10 Obesity was established as a major risk factor for coronary heart disease (CHD) in 1998.
In the midst of the mounting evidence demonstrating the deleterious effects of obesity on health in general, and on the cardiovascular system in particular, research has demonstrated numerous benefits to health by as little as 5% to 10% reduction in initial weight.6 However, survey data show that 33% of men and 46% of women are attempting to lose and maintain weight but approximately only 20% are using a combination of reduced caloric intake and at least 150 minutes of weekly physical activity during leisure time to achieve weight loss.11 These facts highlight the importance of identifying the patient at risk and implementing an early treatment course that may prevent the development of obesity.
This major health problem began to receive increasing attention from the scientific community in the mid-1990s. Indeed, in 1997, a paper was published recognizing obesity as a chronic disease.12 The work of several organizations and policymaking groups helped draw attention to obesity as a health concern; for example, the Institute of Medicine published criteria for evaluating weight-management programs and other organizations published guidelines for treatment.13,14 In 1998, the National Heart, Lung, and Blood Institute (NHLBI) issued the Evidence report,15 which provided empirically based guidelines for the identification, evaluation, and treatment of overweight and obesity in adults. The guidelines are being updated by the NHLBI in 2008. Today, other organizations are becoming involved in this increasing public health concern. America on the Move is a national nonprofit online organization whose goal is to improve the health of Americans by advocating small changes in eating and physical activity routines to promote weight loss or cessation of weight gain. This organization offers free web-based programs and tools to individuals, groups, and communities to encourage changes like decreasing daily caloric intake by 100 cal and increasing daily physical activity by 2,000 steps.16 On the international level, the WHO began addressing the issue through the International Obesity Task Force.17 However, despite all the attention given to this serious public health problem, this problem is not being addressed by clinicians or policymakers to the extent that previous health threats, such as the use of tobacco, have been addressed. When patients’ visits to their family physicians were observed, only one in four received any nutritional counseling.18 Health care professionals can help slow the trend of excess weight by educating and counseling their patients about maintaining a healthy weight and how to use healthy lifestyle measures to reduce excess weight.
This chapter draws on the growing volume of empirical literature pertaining to obesity and the evidence-based guidelines to provide an overview of treatment of overweight and obesity. It begins with a review of the process of identification and evaluation of a patient’s risk status and the selection of appropriate treatment. The major components of treatment are covered: lifestyle modification, which includes dietary, exercise, and behavioral therapy; drug therapy; and surgical therapy. Finally, maintenance strategies to enhance long-term adherence to the lifestyle changes that facilitated the weight loss are reviewed.
IDENTIFICATION AND ASSESSMENT OF THE OVERWEIGHT OR OBESE PATIENTWeight Status
In 1998, the United States adopted the cutoff points for the classification of overweight and obesity based on BMI developed by the WHO.17 These criteria define normal weight as a BMI range of 18.50 to 24.99 kg/m2, overweight as a BMI of
25.00 to 29.99 kg/m2, and obese as a BMI of 30 kg/m2 or more.15,17 Further information specified that Asian populations have a higher amount of body fat than Caucasian populations at the same BMI. This information led the WHO to suggest that persons of Asian descent may have increasing but tolerable health risks at a BMI range of 18.50 to 23 kg/m2, an elevated risk with a BMI between 23 and 27.5 kg/m2, and a high risk at a BMI > 27.5 kg/m2.19 An evidence-based review concluded that BMI should be considered as another vital sign to screen for obesity and overweight and to decide upon treatment options6 (see Display 38-1).
25.00 to 29.99 kg/m2, and obese as a BMI of 30 kg/m2 or more.15,17 Further information specified that Asian populations have a higher amount of body fat than Caucasian populations at the same BMI. This information led the WHO to suggest that persons of Asian descent may have increasing but tolerable health risks at a BMI range of 18.50 to 23 kg/m2, an elevated risk with a BMI between 23 and 27.5 kg/m2, and a high risk at a BMI > 27.5 kg/m2.19 An evidence-based review concluded that BMI should be considered as another vital sign to screen for obesity and overweight and to decide upon treatment options6 (see Display 38-1).
 ▪ Figure 38-1 Age-standardized estimates for obesity by country for persons aged ≥15 years in 2005. (Prevalence statistics taken from http://www.who.int/ncd_surveillance/infobase/web/InfoBasePolicyMaker/reports/Reporter. aspx?id=1.) |
Waist (Abdominal) Circumference
Central or visceral obesity is an excess accumulation of fat in the abdomen that is out of proportion to total body fat.15 Intra-abdominal obesity is considered more sensitive and specific than BMI as a predictor of obesity-related morbidity and mortality20,21; a large waist circumference increases the risk of myocardial infarction, heart failure, and death from all causes in patients with cardiovascular disease.22 Visceral obesity can be measured more accurately by computed tomography or magnetic resonance imaging, but these are expensive and impractical for clinical assessment in a practitioner’s office. NHLBI’s evidence-based report recommended that waist circumference be included with the BMI in the clinical assessment.15 Whether to use these criteria to determine treatment may be a clinical decision made on an individual patient basis. In addition, waist circumference can be a valuable marker to monitor progress in weight loss and provide feedback to the patient.
DISPLAY 38-1 BMI Measurement ProcedureWeight and height measurements, required for the BMI determination, should be taken with the patient wearing undergarments and no shoes. Using the height and weight values, the BMI can be calculated or determined by available normograms.15 The BMI is calculated as follows:
BMI = weight (kg)/height (m)2
The BMI can be estimated in pounds and inches as follows:
[weight (pounds)/height (inches)2] 704.5
Waist circumference is a clinically acceptable method to assess the patient’s visceral or abdominal fat content from baseline through weight loss treatment. Gender-specific cutoffs have been established to identify relative risk for development of obesity-associated risks factors. Men with a waistline circumference greater than 40 in. (102 cm) and women with a waistline circumference greater than 35 in. (88 cm) are at high risk for development of obesity-related morbidity (e.g., type 2 diabetes, dyslipidemia, and cardiovascular disease).23 Because of an increased health risk associated with a smaller waist circumference in Asian populations, these cutoff points have been lowered for persons of Asian descent. South Asian and Chinese individuals have an increased risk at a waist circumference of ≥90 cm (35.5 in.) for men and ≥80 cm (31.5 in.) for women. Japanese men and women are at higher risk with a waist circumference of ≥85 cm (33.5 in.) and ≥90 cm (35.5 in.), respectively.24,25 For Korean adults the suitable cutoff for waist circumference is 85 cm (33.5 in.) for women and 90 cm (35.5 in.) for men.26 Patients of normal weight with increased waist circumference measurements may be at increased risk of cardiovascular disease. Because patients with a BMI of more than 35 kg/m2 exceed the waist circumference cutoffs, these indicators of relative risk lose their predictive power, making it unnecessary to measure waist circumference in this group15 (Table 38-1) for the classification of overweight and obesity with waist circumference incorporated in the relative risk assessment. See also Display 38-2.
Assessment of Cardiovascular Disease Risk Factors
Having established the patient’s relative risk based on the overweight/obesity and abdominal obesity criteria, the third part of the assessment is determination of the patient’s absolute risk status in terms of comorbid conditions or risk factors for cardiovascular disease.
Very High Absolute Risk
Patients who are overweight or obese or have abdominal obesity are considered at very high risk if they have the following disease
conditions: established CHD, presence of other atherosclerotic diseases (peripheral arterial disease, abdominal aortic aneurysm, or symptomatic carotid disease), type 2 diabetes, sleep apnea, or target organ damage in the hypertensive patient. People meeting these profiles require aggressive treatment to reduce their cardiovascular disease risk profiles (e.g., cholesterol-lowering therapy and blood pressure control).15
conditions: established CHD, presence of other atherosclerotic diseases (peripheral arterial disease, abdominal aortic aneurysm, or symptomatic carotid disease), type 2 diabetes, sleep apnea, or target organ damage in the hypertensive patient. People meeting these profiles require aggressive treatment to reduce their cardiovascular disease risk profiles (e.g., cholesterol-lowering therapy and blood pressure control).15
Table 38-1 ▪ CLASSIFICATION OF OVERWEIGHT AND OBESITY BY BMI, WAIST CIRCUMFERENCE, AND ASSOCIATED RISK* | ||||||||||||||||||||||||||||||||||||||||||||||||||
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High Absolute Risk
Patients with obesity who have three or more of the following risk factors can be considered at high absolute risk for obesity-related comorbid conditions: cigarette smoking; hypertension; low-density lipoprotein (LDL)-cholesterol of 160 mg/dL or more, or 130 to 159 mg/dL in the presence of two or more other risk factors; high-density lipoprotein (HDL)-cholesterol less than 35 mg/dL; impaired fasting glucose; family history of premature CHD; and men aged 45 years or older or women aged 55 years or older or of postmenopausal status. The provider should follow the established guidelines in estimating absolute risk status and in treating the identified risk factors,23 which are discussed in detail in other chapters.
Additional Factors That Increase Absolute Risk
The presence of additional risk factors (e.g., physical inactivity and elevated triglycerides) can increase a patient’s absolute risk to a level higher than that estimated from the preceding categories.15,27 Elevated triglycerides in the patient with obesity may represent a common manifestation of a lipoprotein phenotype that includes elevated triglycerides, low HDL levels, and small LDL particles, a pattern considered atherogenic.7,8,27,28 There are several additional factors being investigated for their contribution to the risk profile associated with obesity, for example, excess visceral adiposity, hyperinsulinemia that accompanies insulin resistance, and adipose tissue-released proinflammatory cytokines such as interleukin-1, interleukin-6, tumor necrosis factor-α, resistin, or reduced adiponectin (anti-inflammatory).3,29,30
DISPLAY 38-2 Waist (Abdominal) Circumference Measurement ProcedureThe patient should be dressed in undergarments or in an examining gown. Standing to the right of the patient, palpate the upper hipbone to locate the right iliac crest and draw a horizontal mark just above the upper border of the iliac crest. Cross that line with a vertical mark on the midaxillary line. Place the measuring tape in a horizontal plane (parallel to the floor) around the abdomen at the level of the marked point and hold the tape snug to, but not compressing the skin. Take the measurement at a normal minimal respiration.15
Cardiovascular-Related Conditions Influenced by Obesity
Several conditions related to cardiovascular disease are associated with increased body weight (Table 38-2), for example, CHD, hypertension, and congestive heart failure, and these may require additional medical management. The provider needs to address these conditions and make the patient aware that one’s cardiovascular health is influenced by his or her weight. More importantly, discussing the significant impact of as little as a 5% reduction in weight may provide motivation for the patient to initiate behavior change for weight loss.
Undertreated Groups
Two groups that providers may be reluctant to treat are patients who are older than 65 years and smokers. However, elderly persons who are obese still suffer from an increased burden of disease such as hypertension, diabetes, osteoarthritis (OA) and decreased mobility.31,32 Improved pulmonary function, a reduction in antihypertensive medications, and less pain from OA are benefits derived from intentional weight loss in the elderly people who are obese.33 In particular, therapeutic goals for treatment of elderly patients with obesity should include decreasing abdominal fat and preserving muscle mass and strength.34 Weight reduction improves functional status and reduces concomitant risk factors in the older population in a way similar to that in the younger adult35; therefore, this subgroup should at least receive interventions to prevent weight gain, if not achieve weight reduction. The overweight or obese smoker carries excess risk from obesity-associated risk factors. This patient should be advised to quit, and prevention of
weight gain should be addressed through lifestyle approaches, with the emphasis on smoking abstinence.15 When attempting to address multiple behavior changes, rather than concurrent treatment, an improved outcome may result from a sequential approach that focuses on assisting the patient to stop smoking before initiating behavioral weight-management strategies.36
weight gain should be addressed through lifestyle approaches, with the emphasis on smoking abstinence.15 When attempting to address multiple behavior changes, rather than concurrent treatment, an improved outcome may result from a sequential approach that focuses on assisting the patient to stop smoking before initiating behavioral weight-management strategies.36
Table 38-2 ▪ CARDIOVASCULAR-RELATED CONDITIONS ASSOCIATED WITH OVERWEIGHT AND OBESITY | ||||||||||||||||||||||||||
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CLINICAL EVALUATIONBaseline assessment of the cardiac patient includes the BMI, waist circumference, and cardiovascular risk profile, as well as noncardiovascular conditions, for example, sleep apnea, OA, gallstones, and gynecologic abnormalities. These factors need to be evaluated so that obesity is treated in the context of the patient’s risk profile and existence of comorbid conditions.7 Weight loss frequently ameliorates risks by reducing blood pressure and triglycerides, as well as lessens the impact of other comorbid conditions. Therefore, risk factors should be addressed through weight loss treatment. The NHLBI Evidence report15 includes an algorithm that addresses the treatment decisions based on that assessment (Fig. 38-2). This algorithm is focused on weight-related assessment and treatment and does not include evaluation for other disorders for which the patient may be seeing a health care provider. As noted in Figure 38-2, if the patient’s BMI and waist circumference are in the normal range, these parameters should be measured again in 2 years. For the patient who is of normal weight, brief counseling about prevention of future weight gain should be provided. Knowing that weight gain can be expected from most patients, maintenance of weight is a positive outcome and patients should receive reinforcement for maintaining a healthy weight.
Clinical History
For the patient whose parameters are not normal, assessment needs to include the patient’s history, including prior excess weight or weight fluctuations. If not done previously, a physical examination and laboratory measurements to assess lipid profile, glucose level, and related parameters need to be performed. The provider needs to identify existing cardiovascular disease and the presence of possible end-organ damage.
 ▪ Figure 38-2 Treatment algorithm. 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. (Adapted from National Heart, Lung, and Blood Institute, Obesity Education Initiative Expert Panel on the Identification Evaluation and Treatment of Overweight and Obesity. [1998]. Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: The evidence report. Bethesda, MD: National Institutes of Health.) |
Eating and Physical Activity Patterns
A nutritional and physical activity assessment provides additional information that can be used in the treatment plan. This can be done by having the patient complete a 3-day food and activity diary, which should include two work and one nonwork or leisuretype days. When using a 3-day food and activity diary, the patient needs to be instructed on completion of the diary and the details to be included (e.g., exact amount of food eaten and inclusion of recipes or package labels if the food is unusual). Food frequency, 24-hour dietary recalls and activity questionnaires are another means of assessing past year food consumption or current level of physical activity.37, 38, 39 During the 24-hour dietary recall, the trained interviewer asks the patient to recall every food and drink that was consumed in the previous 24 hours. The interview may be conducted either in-person or via the telephone, is usually unannounced, and typically takes 20 to 30 minutes to complete; this assessment tool may be more commonly used in a research setting.37
Patient Motivation
Before considering treatment options, the patient’s motivation for engaging in weight loss treatment needs to be assessed. Embarking on a weight loss and maintenance program requires a commitment to a change in lifestyle and an investment of resources by the patient and the provider. Moreover, the change is not for a limited time, but rather lifelong. Factors to consider in the initial assessment include the patient’s attitude toward weight loss, prior treatment failures and successes, support system, comprehension of risk posed by weight status, readiness to initiate lifestyle changes,40 self-efficacy for achieving weight loss,41 time commitment, barriers to behavior change,42 and financial issues if the treatment is not covered by insurance. Adverse medical events have been reported as a motivating trigger for initiating weight loss efforts and are in fact associated with greater weight loss and less regain, suggesting that health care professionals might use these occasions as an opportunity to introduce the topic of weight management.43 Individuals experiencing major life events, such as a relocation, change in marital status, and family illness, may find it better to delay initiating a weight loss program until they can focus on the behavior changes required. Those individuals with significant anxiety, depression, or eating disorders (e.g., binge eating or bulimia) may need to be treated for these conditions before initiating a weight loss program, even if health care professionals conduct the program. Patients with eating disorders are best served by a referral to a specialist.44 For the unmotivated patient, the provider needs to review the risks of excess weight and the benefits of initiating treatment and discuss how this treatment may be different and how the patient will be assisted. If the patient remains uninterested in treatment, the provider needs to address coexisting risk factors and initiate management of these, including further weight gain prevention. When the patient is ambivalent about making lifestyle change or initiating a weight loss program, motivational interviewing (MI) strategies, also referred to as reflective listening, can be used.45 This approach, which will be discussed in more detail later in this chapter, requires training of the clinician. Once the assessment has been completed, the treatment plan needs to be considered and discussed with the patient.
Provider Assessment of Patient’s Objectives
The manner and attitude of the health care professional when addressing the patient’s obesity and weight management may be an important determinant of the patient’s receptivity. There is some evidence that health care professionals doubt a patient’s motivation or ability to make lifestyle changes and thus might be nonsupportive of the patient’s goals.46 The patient needs to define the problem and the clinician needs to be nonjudgmental in discussing the behavior and the weight problem. When discussing treatment options with the patient, conveying an empathetic understanding of the challenges that come with the long-term lifestyle changes is important. Finally, eliciting the patient’s objective for the treatment and mutually agreeing on a plan of action for the short- and long term will enhance the probability of a positive outcome.47,48
Environmental Barriers to Weight Loss
Environmental obstacles exist partially as a result of our technologically advanced society where reduced energy expenditure in day-to-day life and increased access to high-fat, high-calorie convenience food in larger portion sizes are common.49 In addition, ethnic minorities might be particularly affected by the living environment. For example, neighborhoods in New Orleans with 80% Black residents had 2.4 fast-food restaurants per square mile compared to 1.5 fast-food restaurants per square mile in communities with only 20% Black individuals. Black neighborhoods had access to six more fast-food restaurants than did mostly White neighborhoods when comparing communities of similar size.50 Recent findings revealed that persons who live in areas with a higher number of fast-food restaurants had a higher BMI compared with persons who live in areas with a higher number of full-service restaurants.51
TREATMENT OF OVERWEIGHT AND OBESITYTreatment Approach
Treatment for obesity can be approached through lifestyle modification, which includes dietary and exercise programs, pharmacotherapy, or surgical treatment. The latter two approaches are adjunctive to lifestyle therapy (Table 38-3). The severity of obesity and presence of comorbidities determine the approach to treatment (e.g., the coexistence of type 2 diabetes, hypertension, or congestive heart failure).7 In the absence of comorbid conditions, patients with a BMI between 25 and 30 kg/m2 can achieve adequate weight reduction through lifestyle approaches. Pharmacotherapy is usually limited to those with a BMI greater than 30 kg/m2 or, in the presence of comorbidities, to those with a BMI between 27 and 30 kg/m2. Surgical therapy is considered for a BMI greater than 35 kg/m2 with comorbid conditions, or when the BMI exceeds 40 kg/m2. However, under certain circumstances, consideration should be given to extending surgical treatment to patients with a BMI between 30 and 34.9 kg/m2 with a comorbid condition that can be cured or markedly improved by sizable or sustained weight loss.52 Pharmacologic or surgical therapy is never used in isolation, but rather is adjunctive to lifestyle modification, which needs to be continued indefinitely after the use of these other treatment modalities.
Table 38-3 ▪ APPROACHES TO TREATMENT OF OBESITY BY SEVERITY AND DISEASE RISK | |||||||||||||||||||||
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Goal of Treatment
The goal of weight loss is not to achieve some cosmetic standard of attractiveness, but rather to reduce morbidity and increase mobility and quality of life. The recommended initial weight loss goal is 10%;6 however, improvement in obesity-related risk factors for CHD can be observed with as little as a 5% loss of initial weight. If a weight loss of ≥10% is not maintained, reductions in total and LDL-cholesterol revert toward baseline.7,53 The rate of loss should be approximately 0.5 to 1 lb/week for the moderately obese and 1 to 2 lb/week in the severely obese.54
It is important to discuss treatment strategies and goals with the patient because these have to be arrived at through mutual decision making, and there could be a discrepancy between the provider’s and the patient’s goals.55 An example would be a 55-year-old woman who has lower body obesity and no additional risk factors but may wish to lose a certain amount of weight that may be unrealistic. This patient may achieve the loss and feel better about her appearance, but if she is unable to sustain this loss, she will regain and feel like a failure. This person may benefit from guidance for a lower weight loss goal and exercise or a plan for stability of current weight. However, if this same woman had central adiposity or presence of risk factors, she should be counseled for achieving a 10% weight reduction. Another scenario might involve an individual without additional risk factors, but a desire to achieve a body weight that is significantly below her current weight and one she has not had since she was in her 20s. The achievement and maintenance of this goal weight is unlikely, as most individuals regain approximately one third of their lost weight in the year after treatment. A patient may benefit from an initial goal of 5% to 10% reduction, and if this is achieved, an additional goal can be established.
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