Management of Obesity
Carolyn Crimmins Hintlian
W. Scott Butsch
Obesity has been a major health problem in industrialized societies and is becoming a global epidemic. In the United States, more than 69% of the population is overweight (body mass index [BMI] 25 to 29.9 kg/m2), 35% obese (BMI ≥30 kg/m2), and more than 6% severely obese (BMI ≥40 kg/m2). The health risk increases when weight gain results in moderate to severe obesity. Mortality rates (all-cause, cardiovascular, and cancer related) closely parallel increases in the BMI once levels of obesity are reached.
Although often viewed as largely a behavioral problem, obesity is becoming better understood as a chronic heterogeneous disease with a more complex pathophysiology than previously appreciated. Often resistant to treatment, the condition results from a failure of normal weight and energy regulatory mechanisms, necessitating a multifaceted approach to management. Weight loss is not a cure, but a goal. The degree of weight loss necessary to achieve many of its associated health benefits can be surprisingly modest, putting the goal within the reach of most persons. Patient requests for advice and medication are best responded to with a comprehensive assessment (see Chapter 10) and an individualized program that takes into account the patient’s overall health status, as well as precipitants, preferences, and lifestyle.
The effective management of obesity starts with a careful workup of the medical and psychosocial dimensions of the problem (see Chapter 10), including a determination of cardiovascular risk (e.g., see Chapter 18). Treating etiologically and attending to concurrent obesity-related medical conditions (e.g., hypertension, hypercholesterolemia, sleep apnea, diabetes, osteoarthritis) are essential (see Chapters 26, 27, 46, 102, and 157).
The goal is to achieve the best weight possible in the context of overall health. With product and procedure claims constantly bombarding persons with weight problems, patients appreciate an evidence-based approach to weight loss that is tailored to
their needs. Knowing the rationale, safety, and effectiveness of available treatment modalities (including popular diets, pharmacotherapy, dietary supplements, endoluminal devices, and surgical approaches) is essential to the design of a safe and effective program. In addition, knowledge of available community resources is helpful in guiding patients to additional sources of support, education, and treatment.
their needs. Knowing the rationale, safety, and effectiveness of available treatment modalities (including popular diets, pharmacotherapy, dietary supplements, endoluminal devices, and surgical approaches) is essential to the design of a safe and effective program. In addition, knowledge of available community resources is helpful in guiding patients to additional sources of support, education, and treatment.
PRINCIPLES OF MANAGEMENT
Goals
Although modest from the patient’s perspective, a 5% to 10% reduction in weight is often sufficient to achieve many of the health-related benefits of weight loss (e.g., reduction in blood pressure, cholesterol, glucose intolerance, osteoarthritic complaints). This medically meaningful goal can be used as an initial target while recognizing that the request for help in losing weight may be part of a complex decision to make significant interpersonal, environmental, and lifestyle changes (see also “Patient Education”).
Strategy
Because it is a chronic disease driven by a complex set of powerful and often incompletely understood etiologic factors, obesity management requires a comprehensive, multidimensional approach and continuous effort that includes a lifelong commitment to lifestyle and behavioral changes. Addressing barriers to weight loss and designing a program that matches the complexity of the patient’s weight problem constitute key strategic elements.
Addressing Adaption to Weight Loss.
Powerful counterregulatory systems defend against body weight loss, making the process of weight loss and maintenance at a lower weight difficult. Not only is there a disproportionate reduction in energy expenditure with weight loss (metabolic adaptation), there is also hormonal compensation. Levels of leptin and anorexigenic hormones (e.g., peptide YY, amylin, and cholecystokinin) decrease, and the levels of the orexigenic hormone ghrelin increase (see Chapter 10). These hormonal changes are associated with an increased urge to eat and overall hunger. Given this physiologic response, it is not surprising that no single measure or particular approach is effective for all persons. There are few predictors of how well a particular intervention may work; however, treatment plans should match the complexity of the individual’s obesity.
Matching Treatment with the Complexity of the Patient’s Obesity.
Despite the variability in response to specific interventions, a few recommendations emerge from consensus panels regarding overall strategy:
For those not ready to lose weight, the best approach is to educate them about health risks, address other cardiovascular risk factors, and encourage the maintenance of their current weight through healthy lifestyle changes. Weight status does not necessarily reflect health status.
For motivated persons, be they overweight (BMI 25 to 29.9 kg/m2) and having at least one obesity-related medical condition, or obese (BMI ≥30 kg/m2), a stepwise approach to weight loss, including more intense lifestyle interventions, can be initiated. The aggressiveness of therapy can be determined by the extent and severity of the weight-related comorbidities, psychosocial and functional limitations, and overall quality of life. Time limits, for example, 6 months, may be set to reach 5% to 10% body weight loss with the understanding of patient-patient variation. Special attention should be given to specific factors contributing to increased body weight, for example, diet, exercise, sleep, and stress. A more targeted approach may center only in one area, for example, poor sleep behaviors if there is a particular strong contribution to increased body weight. Depending on the area of lifestyle modification addressed, referrals to a dietitian, psychologist, social worker, exercise trainer, or sleep specialist, for example, may be necessary. If there is no response to the above lifestyle intervention and a continued weight plateau, one can consider adding pharmacologic therapy (see later discussion).
For persons with severe obesity who are at greatest risk (BMI ≥35 kg/m2 with two or more obesity-related medical conditions or BMI ≥40 kg/m2), a more aggressive approach, including management of comorbidities and consideration of both pharmacologic and surgical weight-loss options, should be considered. A surgical approach may be entertained if repeated attempts using the foregoing measures have been unsuccessful.
One proposed method of assessing obesity-related risks and guiding treatment is the Edmonton obesity staging system. It predicts mortality independent of BMI, focusing on weightrelated comorbidities rather than BMI alone. For example, if an individual with obesity does not have weight-related comorbidities and no psychopathology and functional limitations, prevention of further weight gain, and not weight loss, is encouraged. Further validation and refinement are needed before use in clinical care.
Patient Selection
In most instances, self-selection will determine who undergoes a comprehensive weight-loss program because behavioral change is required. Nonetheless, physician input can play an important motivating role in the question of who should be encouraged most to undergo an intensive program of weight reduction.
One should understand that obesity does not present uniformly across populations and therefore should be treated on an individual basis. Physicians should first assess motivation and individual risks. One suggested approach is to identify persons at greatest health risk, namely, those with signs and symptoms of insulin resistance and the metabolic syndrome. Such persons are at particularly high risk for adverse cardiovascular events, but prognosis, as noted earlier, can be greatly improved through modest weight reduction (on the order of 5% to 10%).
Cardiovascular risk stratification helps identify such persons and is best carried out using a validated risk assessment tool such as the Framingham Score (see Chapter 18), which utilizes independent risk factors such as blood pressure, fasting lipid profile, presence of diabetes, and smoking to determine cardiovascular risk. Complementing this determination is waist circumference, a measure of abdominal fat content. A waist circumference of greater than 35 inches in women and 40 inches in men raises cardiovascular risk.
Other determinants of overall risk include weight-related complications such as obstructive sleep apnea, fatty liver disease, and severe gastroesophageal reflux increase overall risk and help determine treatment options. Not to be overlooked are quality-of-life complications such as osteoarthritis of weight-bearing joints, marked venous insufficiency, and psychosocial dysfunction.
Dietary Approaches (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33 and 34)
“Going on a diet” is the typical first step in weight reduction, but the word “diet” implies that one is making only a temporary change in one’s eating habits and patterns. Patients need to understand that the most effective diet is not a “diet” at all but rather an individualized weight management program that
focuses on the implementation of gradual, permanent lifestyle changes. The focus is a more modular approach looking at not only eating habits but also exercise, sleep duration, and stress reduction techniques that can be followed for a lifetime. The plethora of available and often contradictory diets heavily promoted for their supposed special advantages are only as good in the long run as their degree of caloric restriction and palatability encouraging adherence. The approach to the patient with obesity needs to be a stepwise care plan with lifestyle modification. Durable weight loss is difficult, and its maintenance requires a strong support system and a program of regular exercise.
focuses on the implementation of gradual, permanent lifestyle changes. The focus is a more modular approach looking at not only eating habits but also exercise, sleep duration, and stress reduction techniques that can be followed for a lifetime. The plethora of available and often contradictory diets heavily promoted for their supposed special advantages are only as good in the long run as their degree of caloric restriction and palatability encouraging adherence. The approach to the patient with obesity needs to be a stepwise care plan with lifestyle modification. Durable weight loss is difficult, and its maintenance requires a strong support system and a program of regular exercise.
Some of the most firmly held beliefs promoted in the popular media about weight loss are actually myths and unproven assumptions. For example, the belief that slow gradual weight loss is best for long-term success is contradicted by evidence that very-low-calorie diets result in greater, more durable weight loss. Another myth is that small changes in food intake and/or exercise will produce substantial, continuous weight changes. While small changes may help initially, energy requirements change as body mass changes over time, so, as weight is lost, it takes more exercise and reduced intake to perpetuate the loss.
Determining Daily Caloric Intake
It is easy to gain weight from a very small imbalance in the number of calories consumed over calories used. The desired daily caloric intake needs to be determined. The traditional rule of thumb—reducing dietary caloric intake by 500 to 1,000 kcal/d can produce a loss of about 1 lb/wk—has been superseded by a more realistic model of caloric intake and expenditure, where a reduction of 250 cal/d can lead to a weight loss of about 25 lb over 3 years, with half occurring the 1st year. Individuals with obesity burn their calories less efficiently and likely have to cut more than 500 cal/d to lose weight.
Predictive equations are used in clinical practice to estimate energy needs. Web-based programs are available (see Table 233-1). The Mifflin-St. Jeor equation provides the best estimate of resting metabolic rate to within 10% of that measured.
Dietary Composition.
All weight reduction programs should be nutritionally adequate—except for calories—and include a balanced diet. Most fad diets are neither nutritionally sound nor based on proven scientific evidence. Extravagant claims that a particular food or class of foods dramatically alters weight, appetite, or calorigenesis are unfounded.
The cornerstones of efficacy and safety are a reduction in calories and nutritional balance. Nutrient content and the timing and number of meals and snacks are important determinants for short-term and long-term appetite control. Limiting calories is critical to decreasing body fat and maintaining weight loss.
When following a hypocaloric dietary regimen, the patient must realize that initial rapid weight loss may occur because of a negative fluid balance. After 2 to 3 weeks, the rate of weight loss slows down. Most subsequent loss reflects the catabolism of fat. Loss of fat is directly proportional to the size and duration of the energy deficit. Patients often become discouraged when they enter the slower phase. Most adjust to caloric restriction by unknowingly diminishing their expenditure of energy, one reason an exercise program is such an important adjunct (see later discussion).
Counseling and Medical Nutrition Therapy by the Dietitian
Customizing the weight-loss program to the individual needs of the patient and arranging for follow-up are important to sustaining behavioral change. Nutrition counseling is an essential step in the educational process. It begins with the physician’s endorsement (an essential component that is often overlooked). Patients need to recognize their lifestyle patterns and achieve a basic understanding of the caloric and nutritional contents of foods to be able to choose intelligently. Successful weight loss goes beyond diet choice. Factors like eating behavior, support, and exercise are critical to long-term success. The patient also must also be presented with an approach that focuses on the connections relating body, brain, and appetite. Factors that control appetite include emotionally satisfying food, stress, and exercise.
An essential component of comprehensive management is to have registered dietitians (RDs) provide intensive behavioral counseling for obesity through medical nutrition therapy (MNT). An MNT intervention includes counseling on behavioral and lifestyle changes required to impact long-term eating habits and health. The services of an RD can be beneficial because such persons are specifically trained in assessing nutritional requirements and counseling food selection and preparation. The nutritionist can also review appetite-influencing factors such as exercise and the use of food for emotional satisfaction and stress management. Helping to assess and change attitudes and behaviors toward food and eating are important objectives.
The assessment integrates medical concerns with the patient’s individual and family lifestyle, economic status, learning ability, and psychological needs. An individualized weight control plan is constructed to address specific needs and food preferences. Dietary changes must be gradually implemented to ensure lifelong positive eating habits. Nutrition counseling is likely to increase patient adherence to a dietary regimen and improve outcome.
Beneficiaries who receive such nutrition counseling and interventions exhibit significant improvements in weight and restructured behaviors that impact long-term weight management. Studies show MNT provided by an RD to overweight and obese adults for less than 6 months yields significant weight losses of approximately 1 to 2 lb/wk. MNT provided from 6 to 12 months yields significant mean weight losses of up to 10% of body weight with maintenance of this weight beyond 1 year.
Participation in weight-loss programs with good adherence is the strongest predictor of weight loss. This includes enhanced lifestyle counseling techniques such as the frequency of meetings (can be in person or remote), food records, the inclusion of exercise, diabetes, and calorie recommendations.
Self-Directed and Commercial Weight-Loss Programs
Many commercial and self-directed weight-loss programs are available (see Table 233-1); weight-loss books are constant best sellers reflecting the demand for weight loss. Some commercial and self-directed programs provide menus and a line of foods or supplements to buy; others include individual or group support. Advances in technology have introduced many enhanced lifestyle counseling interventions by telephone, Internet, and e-mail. The use of mobile technologies to deliver behavioral weight-loss treatment appears to be promising. Regarding Internet-based diet programs, interventions appear to be more effective when they include interaction with a health professional (e.g., via e-mail) rather than being limited to Web sites at which patients access information.
Integrated approaches provided over the long term with frequent health care professional contacts and a program that includes moderate diet modification, an exercise program, and a behavioral approach are more effective, especially for mildly to moderately overweight persons. Noncommercial, communitybased group programs offer a low-cost alternative for those who seek the assistance of group support; however, in many instances, little professional guidance is provided. Group therapy has been shown to produce greater weight loss than has individual therapy, even among clients who prefer individual therapy. Compliance remains a key determinant of success, and attendance at group meetings is critical to compliance.
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Dietary Approaches for Weight Management
As noted, there are a host of dietary approaches, differing in composition but sharing the common denominator of a reduction in total calories, the essential determinant of weight loss.
Low-Fat Diet.
A low-fat reduced energy diet is a well-studied weight-loss dietary strategy. It derives from early dietary programs for hypercholesterolemia to reduce coronary heart disease risk. These programs limit total fat, saturated fat, partially hydrogenated unsaturated fatty acids, and dietary cholesterol. They are based on the observation that saturated fat and partially hydrogenated unsaturated fatty acids are major contributors to the production of low-density-lipoprotein cholesterol, with a lesser contribution from dietary cholesterol. Advances in understanding the cardiovascularly beneficial effects of essential poly- and monounsaturates have led to a better appreciation for the importance of fat composition rather than just total fat content of the diet (see Chapter 27).
Low-Carbohydrate Diet.
Taking a truly low-carbohydrate diet high in protein (total daily carbohydrate intake as low as 20 g/d) leads to increased ketone production, which was hypothesized decades ago by Atkins to decrease hunger and increase satiety, the rationale he invoked for his popular diets. More recently, the atherogenic potential and caloric pitfalls of diets rich in the so-called “low-fat” foods and excess carbohydrate intake have rekindled interest in low-carbohydrate diets.
As glycogen stores are depleted in response to low carbohydrate intake, the resultant diuresis produces an initial dramatic weight loss. Having patients focus on reducing carbohydrates rather than reducing calories may be a successful short-term strategy for some individuals. Markedly reducing carbohydrate intake (<35% of calories from carbohydrates) certainly results in reduced energy intake, the sine qua non requirement of weight reduction. Low-carbohydrate diets can lead to slightly more short-term weight loss than just cutting fat and calories; however, such diets are very hard to sustain. Benefit wanes after 6 months, and most people regain lost weight after time. Concern about the high-fat content of some iterations of this diet has led to examinations of its effects on coronary risk factors (see Chapter 27).
Meal Replacements.
For people who have difficulty with self-selection and/or portion control, meal replacements (e.g., liquid meals, meal bars, or calorie-controlled packaged meals) may be used as part of the diet component of a comprehensive weight management program. Substituting one or two daily meals or snacks with meal replacements has been shown to be a successful weight-loss and weight maintenance strategy. They work simply because they limit the number of calories eaten at a meal. Meal replacements also add structure to a person’s eating habits. Structure seems to help some people to stick with a weight management plan. In addition, less time is spent thinking about preparing and eating food.
Very-Low-Calorie Diets.
Very-low-calorie diets are considered for use in persons with a BMI greater than 30 kg/m2 who require major weight loss. These medically supervised diets severely limit calories to between 500 and 800 per day. They consist of 1.5 g of protein/kg of body weight per day and are generally offered as a liquid or partial liquid diet as part of a commercial program (see Table 233-1). Protein-sparing modified fasts, consisting of a protein in the form of lean meat, fish, or fowl, are less commonly prescribed. Very-low-calorie diets achieve rapid weight reduction with preservation of lean body mass. Patients can achieve 15% to 25% weight loss within 3 to 4 months and then are reintroduced to solid foods with a higher caloric content. Weight regain, up to 40% to 50% of the lost weight after 1 to 2 years, may occur, especially in absence of close supervision. The very-low-calorie diet is not recommended for children, adolescents, pregnant or lactating women, or the elderly. It should be avoided in individuals who are overweight and those with type I diabetes, pancreatitis, severe renal or hepatic impairment, active cancer, or a severe psychological disturbance. Caution should be used in those with cardiovascular disease, especially congestive heart failure, and those who require chronic steroids. High dropout rates and poor longterm maintenance are discouraging aspects of this form of treatment.
Diets for Maintenance of Weight Loss
Once weight loss is achieved, attention needs to focus on maintenance of weight loss. A combination of diet and exercise appears to be most effective. Among dietary measures, randomized controlled study finds a dietary program of modest increase in protein content and a modest reduction in glycemic index achieves the best results with regard to compliance and weight, when compared with a low-protein/low-glycemic diet, a lowprotein/high-glycemic diet, a high-protein/high-glycemic diet, or a control diet.
The aim of the behavioral approach is to develop alternative eating behaviors that are practical and lead to a decreased caloric intake and increase physical activity. Strong evidence exists to support the use of a combination of behavioral theory and cognitive-behavioral theory in facilitating modification of habits. Key features of behavioral therapy and cognitive-behavioral therapy programs include the following:
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