Managing Weight Across the Spectrum of Eating Disorders
By Mary K. Stein, Managing Editor
During a plenary session, four eating disorders experts explored the many challenges weight and weight management pose for eating disorders patients and clinicians alike. Anne Becker, MD, who chaired the discussion, said, "New data suggest that dieting may have a very different role and place in the treatment of eating disorders than we originally thought."
The problem, she said, is that "clinicians must now navigate weight management in the context of both medical compromise and psychological distress. In addition, they must evaluate the risks and benefits of weight management in the context of radically shifting recommendations on dietary guidelines, physical activity and what even is a "healthy body weight." To make it even more challenging, clinicians must add what Dr. Kelly Brownell has described as our ‘toxic food environment,' she said. Finally, Dr. Becker added, "No matter which side of a healthy body weight our patient is on, and no matter how much we think we know where we want that patient to be, it often seems impossible to get the patient there."
Using Anthropometric Measurements
Maria Teresa Rivera, RD, offered guidelines and suggestions for using anthropometric measurements to track treatment progress for individual eating disorders and patients of all ages. Often what is valid for one ethnic group is invalid for another, she said.
Rivera noted that with patients with binge eating disorder (BED), a question often arises—is body weight or binge frequency the primary outcome measure? In this patient group, the treatment team should determine the chances of successful weight loss, she said. If chances of success are minimal, then dieting will have a negative effect on the patient. She added that useful anthropometric measurements to determine fat distribution include: waist circumference or waist-hip ratio and body mass index (BMI) to determine the degree of obesity.
"Whether the primary goal in treatment is binge cessation or weight loss, we have to be aware of health risks associated with obesity," Rivera said. She added that body mass index (BMI) measurements are useful in adults, children, and adolescents. A cutoff value above the 95th percentile of normal weight is a useful screening tool for medical problems, and can help identify children who need further medical assessment, she added. Standard BMI values are, however, not necessarily valid for all ethnic groups, she said, adding that among non-Caucasian populations, a higher-than-normal prevalence of comorbidities is seen at BMI values considered normal for Caucausians. This has been described in populations with a high prevalence of short stature, she added. For example, 30% of Mexico's population is short in stature. Thus, BMI is a less sensitive tool for detecting cases of obesity-associated comorbidities in shorter subjects than among people of standard heights.
Waist circumference is a better discriminator than BMI for use in public health screening, according to Rivera. She also pointed out that the risk for diabetes and hypertension starts at lower levels of waist circumference than those suggested by the World Health Organization, and the suggested guidelines are only somewhat helpful for measuring waist-hip ratios in some populations. She said, "We have to be alert to the need to begin screening for obesity-associated comorbidities. Uniform definitions are useful but the issue is at what point should clinicians be alerted to the need for further medical assessment?" BMI, waist-hip ratio, and waist circumference are all useful measurements to include at the initial assessment and if the patient is ready for change, these might be used to help monitor progress, she added.
Among patients with bulimia nervosa (BN), treatment is not focused on maintaining a particular weight, but rather aimed at finding a healthy weight patients can maintain, according to Dr. Rivera. For these patients, regular exercise and eating a healthy diet can work once patients are ready to challenge cognitive distortions and to identify weight-food situations, she said.
For patients with anorexia nervosa (AN), Rivera advised clinicians to remember that when initially assessing weight, the standard criteria of 85% of healthy BMI may not have equivalent biological significance at all stages of development, and can lead to misclassifications in adolescents. Although the 70th percentile of the BMI has been proposed as a cutoff point for underweight, Rivera advised that an important issue to consider about weight at initial assessment is its prognostic significance. She noted there are no good guidelines for determining a target weight, and weight range should be established on an individual basis. Among adolescents, there are wide variations in what constitutes a ‘healthy weight,' she said.
If clinicians want to establish a target weight at the beginning of treatment, there are three good reasons for trying to attain 100% of healthy estimated weight, she said. First, setting targets lower than 100% results in persistent amenorrhea in a large percentage of adolescent girls. Second, the impact of adequate weight restoration is important in bone health. Patients discharged at BMIs below 19 are more likely to relapse.
Skinfold thickness is based on fat mass and fat free mass, which have theoretical implications in relation to target weight and outcome in AN, according to Rivera. "Fat mass, as we all know, is the energy reserve and is related to endocrine dysfunction—but we don't know the exact amount of fat needed for restoration of menses," she said. And low fat free mass has been implicated as a major risk for osteoporosis. She added, "In clinical practice, we could determine the percentage fat and other markers of muscle mass or fat mass used in skinfolds and circumferences, but usefulness and validity of skinfolds will depend on the use of proper standards. Not all skinfold equations are valid for every population—and marked edema will confound its accuracy," she said.
Refeeding AN Patients
Janice Russell, MBB, MD, told the audience that working with an AN patient is reminiscent of a Russian doll, which contains a doll within a doll within a doll. Treating persons with AN involves dealing with many layers of psychological problems, psychological changes, physiologic factors, and behaviors, she said.
Among the challenges is restoring endocrine function. Primary and secondary amenorrhea is another challenge, and BMIs aren't useful in all groups; for example, among boys, BMIs can't be used to predict the percentage of fat.
How fast should weight be regained? At her hospital, Royal Prince Alfred Hospital, the clinicians aim for a gain of 0.7 kg a week. While this might seem slow, Dr. Russell pointed out that it is more important too balance weight gain so it doesn't occur too quickly. Most of her patients spend much more time as outpatients than as inpatients, she said, mostly in day programs and in the care of their family physicians.
Dr. Russell stressed the importance of talking with patients and their families about target weight goals, and emphasized that the real goal is to restore body function. She added that it is important to periodically reassess the family's situation. For example, although the parents may have been able to handle the situation when their daughter was 12 or 13 years old, when she is 15 and they no longer feel in control, it might be more appropriate to find a more developmentally appropriate treatment setting. Parents also have many questions, including whether their daughters can continue in ballet or run marathons, even when the girls are very emaciated. Parents need to know that this is not healthy, said Dr. Russell. [Note: The International Olympic Committee, IOC, and the American College of Sports Medicine each have useful guidelines for healthy exercise for patients with eating disorders.] Parents and clinicians also need to discuss medications and the impact of alternative medications.
Dr. Russell told the audience that AN can create a vicious cycle when a patient reaches a BMI of 17 or 17.5. At this point, appetite is poor, constipation occurs, and patients can become hyperactive, interfering with weight gain. Dr. Russell also noted that at this point a significant number of patients find themselves binge eating, and they have to be advised to try to not fight this. Getting patients to eat is all about rewards and eating sensibly, she said. Parents can be good role models at the table, she added.
Dr. Russell and colleagues try to avoid enteral-parenteral feeding unless it is absolutely necessary. Many have peripheral edema, particularly if they have abused laxatives and secondary hypoaldersteronism has developed. It may take as long as 6 weeks to get the antidiuretic hormone (ADH) levels back to normal, she said.
An important part of refeeding AN patients involves metabolic repair, Dr. Russell added. Diet-induced thermogenesis means higher daily requirements for patients. Many of these patients exercise excessively and have higher resting energy expenditure, probably due to metabolic repair. They have a metabolic inflexibility and are unable to turn off fat-burning. Thus, exercise is not a good option in this population, she added. In addition, diet-induced thermogenesis suggests that they should only eat once or twice a day to conserve energy, but this is impractical, of course, she said.
In her follow-up surveys, patients report they like having their meals supervised and like to talk with other patients and the nursing staff. "They never indicate that they like family therapy, medications, or individual therapy, " she laughed.
Dr. Russell stressed the importance of matching patients to treatment and working to rearrange reward systems. When the body's needs for active rewards, such as food, rest, or water aren't being met, Dr. Russell theorizes that patients turn to substance abuse, alcoholism, or shoplifting. All are perverse methods of gaining ‘rewards' when the body's needs aren't met, she said.
Do the New Fad Diets Work?
Caroline Apovian, MD, noted that at any one time from 40% to 50% of women in the U.S. are dieting and that many are looking for a "quick fix." Dr. Apovian evaluated the four most popular diets: the moderate-fat, reduced-calorie diet, the low-fat, high carbohydrate diet (Ornish diet), the low-carbohydrate, high-fat diet, such as the Atkins, South Beach, and Zone diets, and the Mediterranean diet ("good fat versus bad fat diets").
Each of the fad diets has drawbacks, she said. With low-fat, high-carbohydrate diets, even though there are fewer calories in plant-based foods, nutrient intake is lower than the recommended daily amounts. In high-protein, low-carbohydrate diets, most of the initial weight loss is water loss due to increased ketosis and decreases in insulin levels. Another drawback is that the lack of carbohydrates translates to low fiber intake, she said, adding that fiber is important in cardiovascular health, and can decrease the incidence of certain cancers. Fiber is also essential for colon health. The added increase in iron stores may also increase the risk of atherosclerosis. The South Beach Diet is probably the best of the high-protein fad diets, she said, adding that it includes three phases, which increase carbohydrates and also includes olive and canola oils.
How Well Do They Work?
Dr. Apovian cited a recent article in JAMA that evaluated the long-term success of the four diets. The researcher concluded that all diets had similar rates of success—from 20% to 25% of subjects maintained their weight loss over 1 year.
The work of Friedman and colleagues with the Weight Control Registry provides some guidelines for successful dieting, she said. In this study, 5,000 participants have lost at least 30 lb and have kept it off for one year. "The structured program is the key," Dr. Apovian said. To keep the weight off, participants eat a low-calorie diet, and 78% eat breakfast every day. Participants have found they need to burn 400 kcal with exercise each day. She added that most diets fail because people don't follow the structure of reduced calories and increased activity. Without this combination, any diet will fail, she said.
A final panel discussion and question and answer session was led by Dr. Michael Devlin. Dr. Devlin pointed out that each person has a different vulnerability to obesity, as shown by undernourished children in the same family as overweight mothers. He also pointed to the decline of subsistence farming and increase of energy-rich nutrient foods as an underlying reason for the increase in obesity. Body weight is only one part of the equation, he said.