Classification of obesity was proposed by an expert panel convened by the National Institute of Health, National Heart, Lung, and Blood Institute (NHLBI) in 1998 after extensive review of health complications associated with this condition (19
). The panel classified obesity and overweight status based on BMI and waist circumference. Associated disease risk is shown in Table 59.1
). Obesity is technically defined as an excess of body fat (>25% of body weight for men and >30% for women), rather than an excess of body weight in itself (19
). However, the measurement of percentage of body fat is more difficult to obtain and is not as intuitive as body weight. Thus, relative weight is a reasonable surrogate measure for adiposity. Measuring weight adjusted for height, or BMI, defined as weight in kilograms divided by the square of the height in meters, is usually the first step in assessing obesity and is very useful for diagnosing and grading the severity of the condition and its attendant risks (see Table 59.1
). Although BMI is the standard measure of relative weight, it may overstate the actual degree of adiposity in very muscular people (e.g., certain types of athletes and laborers), and it may understate adiposity in very sedentary individuals with little muscle mass. The latter is called sarcopenic obesity,
characterized by a normal or low BMI with increased percentage of body fat and reduced lean body mass. A BMI of 25 to 30 kg/m2
is defined as overweight, 30 to 40 kg/m2
as obese, and 40 kg/m2
or higher as severely or morbidly/grade III obese (20
Waist circumference is the second step in the assessment of obesity. A waist circumference larger than 88 cm (35 in) in women and larger than 102 cm (40 in) in men constitutes abdominal or visceral obesity and is associated with an increased risk of health complications (20
). Waist circumference can be easily measured with a tape rule around the widest point above the hips. In the case of abdominal fat deposition, even mild excess adiposity may pose medical complications, such as increased risk of hypertension, dyslipidemias, and type 2 diabetes (10
). Visceral obesity can exist even in the absence of overall obesity (i.e., at BMIs below the cutoff points for obesity or overweight) (10
). With visceral obesity, even with a normal BMI, it is probably best to encourage weight loss for medical reasons, especially if the patient already suffers from complicating medical conditions or has a strong family history of diabetes, cardiovascular, or cerebrovascular disease. For patients with cosmetic or trivial obesity, the benefits (and motivators) for successful weight loss are more psychosocial than medical. These patients should be encouraged to focus on a healthier diet (with low refined carbohydrate, low saturated fat, and high fiber) and increased physical fitness rather than just the number on the scale.
Psychosocial and Behavioral Assessment
A psychosocial and behavioral assessment should be performed because it can provide considerable information about the patient’s readiness to lose weight as well as identify disordered eating behaviors. Obese individuals commonly exhibit depression, with the degree of severity often greater with severe obesity (23
). A behavioral
psychologist or other skilled professional can inquire into depressive symptoms by asking about the patient’s mood and related symptoms and signs or assessing depression with formal tests (26
). Obese persons with significant depression should be provided appropriate treatment (cognitive behavior therapy or pharmacotherapy) before or during weight reduction efforts.
TABLE 59.1 CLASSIFICATION OF OVERWEIGHT AND OBESITY BY BODY MASS INDEX, WAIST CIRCUMFERENCE, AND ASSOCIATED DISEASE RISK
DISEASE RISK RELATIVE TO NORMAL WEIGHT AND WAIST CIRCUMFERENCE
MEN <102 cm (<40 in)
MEN >102 cm (>40 in)
WOMEN <88 cm (<35 in)
WOMEN >88 cm (>35 in)
BMI, body mass index.
Adapted with permission from National Institutes of Health, National Heart, Lung, and Blood Institute. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults—The Evidence Report. National Institutes of Health.
Approximately 30% of obese individuals who seek weight reduction suffer from binge eating disorder
). Binge eating is characterized by consumption of large amounts of food until one is uncomfortably full and eating alone when not hungry. In addition, patients have a loss of control over eating behavior and a negative emotional state after the binge (27
). Other clues to the presence of an eating disorder or binge eating disorder include altered body image (believing one is obese when one is not) and obsession with one’s body weight (recurring thoughts or weighing oneself multiple times daily). When purging (vomiting or using laxatives or diuretics) or compulsive exercise is used following binging to control weight, bulimia nervosa,
rather than binge eating disorder, is the likely diagnosis. Although anorexia nervosa and bulimia nervosa are commonly recognized as serious eating disorders (28
), binge eating disorder is more common and often occurs in those who are overweight or obese rather than underweight. Merely prescribing a diet is usually not helpful and may even be counterproductive in an obese patient suffering from this disorder. Referral to a specialized treatment program may be helpful. Specific cognitive behavioral therapies have been developed for the treatment of binge eating disorder (29
); however, the condition often responds favorably to a structured, individualized weight loss program along with behavioral therapy. Behavioral evaluation also may identify situations, feelings, or other issues that lead to inappropriate eating (i.e., eating that is not triggered by hunger).
Evaluating Dietary and Activity Habits
A complete dietary and physical assessment is helpful in evaluating the contribution of these factors to weight gain in an obese individual (30
). This assessment can identify problem areas related to diet and exercise that may need modification to lose weight. Formal methods of assessing diet intake including 24-hour recall, 7-day food records, food frequency questionnaires (FFQs), and structured interviews (31
) can help to determine the obese person’s current food choices and eating habits. Moreover, general discussions such as talking about past dieting experiences (if applicable) and asking the reason the patient thinks that he or she was not successful in the past can help in learning more about the patient’s motivations, needs, and barriers to change.
It is important also to ask about current medications, including over-the-counter or prescription drugs, herbs, and vitamin or mineral supplements if any. This information can help assess for potential food-drug interactions, assess daily intake in relation to nutrient requirements, and assist in the evaluation of methods used to address weight and nutritional issues by the patient. Often, an obese person reveals more information to a dietitian when specifically probed to answer these questions than when meeting with a primary health care provider. Any food allergies or intolerances (e.g., gluten, lactose) also should be covered.
Different dietary assessment methods have their strengths and limitations. For example, a 24-hour diet recall is helpful in assessing food and beverage intake, including the type and amount of food, brand names of foods, cooking methods, time of day, and location of eating (31
). Multiple-day food records or food diaries assess food and beverage consumption over a period of typically 3 to 7 days, and intake is recorded either before or after eating. It is helpful for both the patient and the clinician to discuss how to measure or estimate food portions appropriately to create accurate accounts of food consumed and to document as many aspects of the food as possible (e.g., method of food preparation, type and amount of condiments used, name brands, restaurant names). Behaviorally relevant information also can be recorded in multiple-day food diaries, including an assessment of hunger levels before and after eating, in addition to feelings, thoughts, and situations surrounding the eating event. Nutritional information and calculations can be included, such as calories, fat grams, carbohydrate servings, sodium, and others. Accuracy depends on the person’s memory, completeness of reporting, and the interviewing and communication skills of both the patient and the evaluator.
The data gleaned from any dietary assessments should be interpreted with caution, however, because retrospective and even prospective underreporting and overreporting are common. FFQs are self-administered tests with multiple questions about frequency of consumption and portion size of many different foods over the prior 1 month or 3 months. Questions in FFQs also may include information on food purchasing and preparation methods. FFQs can help identify inadequacy or overconsumption of specific food groups, or patterns of specific foods or preparation methods. Like the food diary, the FFQ can offer a more real-life assessment of the patient’s typical food choices because it can be completed outside of the provider’s office.
Reduced levels of physical activity can be a major factor in the etiology of obesity and may be a direct result of acute or chronic illness, job change or retirement, or just sedentary lifestyles in general, such as more television viewing or screen time (34
). An inventory of the person’s usual physical activity and preferred forms of exercise can identify opportunities for increasing the level of energy expended through physical activity. Food record forms can include a place for physical activity, which can be helpful in discussing exercise habits and goals. However, the provider must recognize and communicate that exercise alone is, unfortunately, not an effective method for losing weight. It is difficult for the untrained person to do enough of it, and most, if not all, of the expended
energy may be compensated by increased caloric intake. Exercise is a very good way to maintain a lower weight after weight loss, thus enabling a person to eat somewhat more than a nonexerciser and maintain weight. Regular aerobic exercise and strength training also will improve cardiovascular fitness, trim inches, and promote growth of metabolically more active muscle tissue.
The exercise assessment should include a record of the usual degree of physical activity, any limiting factors such as joint disease or previous injuries, types of activity the patient finds enjoyable, and a measurement, preferably by an exercise physiologist or certified trainer of the current fitness level. Physical activity level can be assessed broadly by inquiring about the amount of walking done in a day, flights of stairs climbed, and hours of television watched (38
). More formal assessment can be conducted using a pedometer to determine the number of steps walked daily, or an accelerometer, which also can assess the intensity of activity.
A rule of thumb in prescribing an exercise regimen is to use a phased-in approach. Most obese patients start out with a limited capacity to exercise. Rather than suggesting a type or level of activity that is unlikely to maximize adherence, make sure that the plan fits the patient’s current abilities, schedule, and lifestyle. The first phase often consists of increasing the amount of everyday physical activity, so-called lifestyle activity, without introducing a formal exercise regimen. Lifestyle activities include taking the stairs in gradually increasing fashion, parking the car farther away from the destination, walking to the mailbox, and the like. This phase alone may double the level of physical activity in a very sedentary person.
The next phase is a walking plan. People are most likely to comply with such a plan if the walk is scheduled during typically available times, such as a break or lunchtime during work hours. Scheduling exercise when the individual’s daily energy level is the highest (e.g., early morning for many people) is often more effective than at the end of a long day. Having a companion to walk with and a place to walk indoors also are helpful in increasing adherence.
One half hour is a good minimum time to recommend that a patient should make available for each session of exercise. An hour or longer is best for weight control. The intensity of the exercise is not critical to the burning of calories: walking at a leisurely pace for 1 hour is roughly equal to walking briskly for half an hour. Allow the patient to set the pace. Initially, it may be quite slow, but in the absence of severe pulmonary, cardiovascular, or joint disease, most patients soon find the going easier and faster. Goal setting can strengthen this reinforcement. Having the patient keep a log of the time spent walking and the distance covered after each session is useful. The patient can then see the progress being made and can set the goal a bit higher as warranted.
In the next phase of a progressive exercise plan, the types of activities performed should be broadened. Walking or jogging can and should remain a feature at this stage, but with the addition of other forms of aerobic exercise. Perhaps recommend aerobics classes, stationary or outdoor bicycling, swimming, a cross-country skiing machine, or just about anything else that will burn calories and be enjoyable to the patient. Team or racquet sports and golf can be suggested to provide social interaction, as well as to increase energy expenditure. Again, the most important criterion for a good exercise plan is one that the patient is likely to follow and be comfortable with as a lifelong habit.