Gastroenterology and Hepatology Board Review: Pearls of Wisdom, Third Edition
Section VII NUTRITION
CHAPTER 44. Obesity and Eating Disorders
David J. Frantz, MD, MS and Tamar Ringel-Kulka, MD, MPH
What are the types and subtypes of eating disorders (EDs)?
The Diagnostic and Statistical Manual of Mental Disorders IV (DSMV-IV) defines three categories of EDs: anorexia nervosa (AN), bulimia nervosa (BN), and EDs not otherwise specified (NOS). AN is further divided into restricting and binge-eating/purging subtypes. BN subtypes are purging and non-purging. Binge eating disorder (BED) is an entity currently part of NOS and may be considered as a separate entity in the future. The International Classification of Diseases 10 (ICD-10) uses different categories including AN, BN, and atypical ED.
What are the underlying mechanisms of EDs?
AN and bulimia are multifactorial disorders that result from a combination of biologic, genetic, psychological, familial, social, and environmental influences. Psychiatric comorbidities are common among the EDs.
What are the DSM-IV criteria for AN?
• Refusal to maintain body weight at or above 85% of expected body weight for age, height, and sex.
• Fear of gaining weight and becoming fat despite being underweight.
• Distorted body weight and shape.
• Amenorrhea or absence of at least three menstrual cycles.
What are the DSM-IV criteria for BN?
• Recurrent episodes of binge eating.
• Engagement in compensatory behavior to prevent weight gain.
• Occurrence of episodes twice weekly for at least 3 months.
• Disproportionate estimation of body size.
• No AN episodes.
What are some characteristics of BED?
• BED is more common than AN and BN.
• Occurrence of episodes at least twice weekly for 6 months.
• Patients feel lack of control over eating, feel guilty, and/or disgust from their behavior.
• Patients do not engage in compensatory behavior to prevent weight gain.
• Patients are often obese [body mass index (BMI) > 30].
What are the major differential diagnostic considerations in EDs?
• Inflammatory bowel disease (IBD)
• Celiac disease
• Marked increased physical activity
• Diabetes mellitus
• Chronic infections
• Pituitary prolactinoma
• Pregnancy (hyperemesis gravidarum)
• Addison disease
• Substance abuse
• Depression and/or obsessive compulsive disorder (OCD)
• Malignancy including central nervous system (CNS) tumor
• Superior mesenteric artery syndrome (also a sequela)
• Gastric outlet obstruction
What is the incidence and prevalence of AN in the United States? Has it changed over the years?
Incidence rates for females 15–19 years of age range from 20 to 74 per 100,000 person years. The incidence rate is believed to have been increasing over the past 50–60 years, particularly in women aged 15–24. There is mixed data regarding the last few decades, partly due to more strict definitions of the disorder. The lifetime prevalence is approximately 0.9% among women and 0.3% among men in the United States. Most authors agree that only a fraction of patients with the disorder come to medical attention.
When is the usual onset of presentation of the EDs?
Median age of onset of all EDs is between 18 and 21 years; however, they can occur at all ages.
What is the male to female ratio in AN?
The difference in lifetime prevalence between females and males with anorexia is thought to be less than previously reported in the literature. In one recent study, the ratio in the United States was reported as 3:1.
Describe the differences in attitude concerning weight in patients with other psychiatric or organic disorders compared to patients with EDs.
Those with disorders other than EDs:
• Are concerned about their weight loss.
• Do not try to prevent weight gain by restricted diet.
• Do not engage in excessive exercise.
• Do not have distorted body image.
True/False: Anorectic patients will engage in self-induced vomiting or take purgatives.
True. In bulimic-type AN, weight loss is accomplished in these ways about half of the time rather than with restriction and exercise.
True/False: Anorectic patients do not experience the sensation of hunger.
False. Anorectic patients do feel hunger; however, in their pursuit of thinness, they struggle against hunger to achieve an unrealistic degree of weight loss.
What physiologic measures are decreased in anorectic patients?
Core temperature, blood pressure, pulse rate, bowel sounds, and gastric emptying rate.
What is the most common endocrine abnormality in AN?
Amenorrhea is the most common endocrine abnormality in anorectic patients. The origin of amenorrhea is due to hypothalamic-pituitary dysfunction. Serum levels of estradiol, follicle-stimulating hormone, and luteinizing hormone are lower than in healthy individuals.
True/False: Amenorrhea may precede weight loss.
True. In about one-third of the patients, amenorrhea precedes weight loss. Stress appears to cause psychogenic amenorrhea prior to the onset of weight loss.
True/False: Amenorrhea always resolves after achieving ideal body weight.
What signs of health compromise in ED patients should prompt recommendation of hospitalization?
Urgent care is based on the existence of medical, psychiatric, and behavioral factors that do not enable treatment in outpatient facilities. Specific criteria may include the following:
• Weight Criteria:
< 85% of healthy body weight for age, height, or sex
Excessive decline in weight together with food refusal regardless of current BMI
BMI < 13 kg/m2 or BMI < 2nd percentile
• Physiologic Criteria:
Blood pressure < 80/50 mmHg
Postural hypotension drop > 10–20 mmHg
Heart rate < 40 beats/min
Oxygen saturation < 85%
Electrolytes below minimal normal level
Body temperature < 34.5°C
Electrocardiogram abnormalities such as a prolonged corrected Q-T interval (QTc) or T wave changes
Subjects needing supervision due to suicidality, and/or supervision during or after meals
Patients who are uncooperative and/or poorly motivated
What are the causes of death in EDs?
There are limited data on the specific causes of death, but in aggregate, it is thought that about half of the patients die from complications of their EDs such as starvation, heart failure, cardiac arrhythmia, or renal failure. Less than a third commit suicide and about a fifth die from unknown causes.
True/False: Electrocardiographic abnormalities are common in AN.
False. Although various electrocardiographic abnormalities have been described in AN, most patients who are not chronically vomiting or abusing laxatives will have a normal electrocardiogram. Prolongation of the QTc interval is the main predictor of risk of sudden death especially when combined with hypokalemia.
True/False: The primary goal of nutritional intervention in AN is to slowly get the patient to a body weight out of the range of medical risk.
True. The refeeding should be slow and the patient must be carefully monitored for refeeding syndrome. Weight gain should be gradual rather than rapid. Initially, patients generally require a soft diet with both multivitamin and mineral supplementation.
What are the common long-term morbidities associated with AN?
Osteoporosis is a common morbidity due to hypoestrogenemia along with nutritional deficiencies. Other common sequelae are dental problems, growth retardation, infertility, perinatal complications, and increased psychosocial impairment.
What behaviors may BN patients exhibit to prevent weight gain?
• Regularly self-induce vomiting
• Abuse of laxatives, diuretics, diet pills, and other medication in efforts to reduce weight
• Excessive exercise
True/False: Constipation is one of the acute gastrointestinal complications in patients with BN.
False. Constipation is a chronic complication of AN. Mallory–Weiss tears with acute gastrointestinal bleeding and Boerhaave’s syndrome are potential acute gastrointestinal complications of BN.
What is a common metabolic complication seen in BN patients?
Hypochloremic, hypokalemic metabolic alkalosis. This is due to regular/excessive vomiting.
What are typical signs that can be recognized on physical examination in BN patients?
Russell sign (excoriation on the dorsum of hands or fingers), loss of dentine on the lingual and occlusal surface of the teeth, and parotid gland hypertrophy.
True/False: The incidence and prevalence of BN are lower than that of AN.
False. The incidence and prevalence of BN are higher than that of AN. The lifetime prevalence of bulimia is 1.5% in females and 0.5% in males.
True/False: Unlike anorectic patients, BN patients have normal body size.
True. Bulimic patients usually have normal body weight, less body image distortion, greater awareness that their secret compulsive behaviors are aberrant, and greater acceptance of treatment compared to anorectic patients.
True/False: Satiety interrupts binging episodes in bulimic patients.
False. The binge-purge cycle is an eating compulsion associated with failure to achieve or respond to normal satiety. The episodes occur secretly, are planned, and are terminated by a feeling of guilt or physical discomfort.
What predicts the long-term prognosis of EDs?
For AN patients, the younger the onset and the shorter the duration, the better the outcome. In BN, the opposite is true; the longer the duration of the illness, the higher the recovery rate. One study found that about a third of BN and BED patients continue to have active ED 12 years after diagnosis. Another study showed that about a fifth of anorectic patients continued to have difficulties in everyday life 10–20 years after onset.
True/False: Multidisciplinary treatment is recommended for AN.
True. Multidisciplinary treatment is the experts’ recommended treatment for AN. Family-based therapy (Maudsley) gained moderate level of evidence on its efficacy. Pharmaceutical intervention with atypical antipsychotic drugs to target dopaminergic dysregulation and comorbid features reduce distorted cognitions and anxiety symptoms, and therefore reduce the resistance to weight gain.
What is the recommended treatment for BN and BED?
There is strong evidence of efficacy for cognitive behavioral therapy (CBT) in treating BN and BED. For the acute phase of BN, selective serotonin reuptake inhibitors (SSRIs) appear efficacious; however, there is not enough data on their long-term utility. There is moderate evidence for the use of pharmacotherapy in the treatment of BED. This includes the use of antidepressants (SSRIs—slight benefit) and anticonvulsants (topiramate—moderate benefit) to reduce binge episodes. Appetite suppressants such as sibutramine show a moderate benefit on weight loss.
True/False: AN has increased mortality and persistent psychiatric disorders compared to other EDs.
True/False: Fifty percent of obese people who lose weight on a well-designed program of diet and exercise will maintain their achieved weight.
False. Ninety to 95% of persons who lose weight subsequently regain it within 5 years.
What measure is commonly used to define obesity?
Body mass index (BMI).
What are the BMI classifications of normal weight, overweight, and obesity?
What health risks are associated with obesity?
The risk of stroke, ischemic heart disease, and diabetes mellitus in patients with a BMI > 28 is three to four times the risk of that seen in the general population. In addition, obese patients are at increased risk of obstructive sleep apnea, osteoarthritis, gout, cancer, chronic kidney disease, gallstones, nonalcoholic fatty liver disease (NAFLD), and gastroesophageal reflux disease (GERD).
True/False: The distribution of fat over the body is important with respect to morbidity and mortality.
True. A higher risk of morbidity and mortality is more strongly associated with a central distribution than with a peripheral distribution of body fat.
True/False: Adipose tissue is an endocrine organ.
True. Active research into obesity has revealed that adipose cells have a potent endocrine function producing multiple adipokines, which primarily work in conjunction with central nervous system and gut hormones to control hunger, satiety, and lipid metabolism. Adipokines exert a pleiotropic effect on the body and may play a role in inflammation, immune response, vasoregulation, insulin resistance, and the development of metabolic syndrome. Three important adipokines include leptin, adiponectin, and tumor necrosis factor (TNF)-alpha.
True/False: The goal when treating obesity is to achieve normal body weight.
False. The goal is reduction of health risks. Even modest weight loss can alleviate symptoms from obesity-related comorbidities.
True/False: A calorie- and fat-reduced diet is the most successful nonsurgical treatment for obesity.
False. Data are insufficient to recommend any specific diet. A multidisciplinary individualized approach including nutrition counseling, regular activity, and reinforcement of behavioral modification is considered the most successful nonsurgical approach.
When is bariatric surgery recommended?
The consensus guidelines from NIH published in 1991 are still generally accepted today. These include the following:
• Well-informed and motivated patient.
• Patient’s BMI > 40.
• Patient’s BMI > 35 and existence of serious comorbidities such as sleep apnea, cardiomyopathy, joint disease, or diabetes.
• Patient has acceptable risk profile for surgery.
• Patient failed previous nonsurgical methods of weight loss.
What are the roles of the counter regulatory hormones ghrelin and leptin?
Ghrelin is produced in the stomach and promotes hunger. In contrast, leptin is derived from adipocytes and helps reduce hunger. In obesity, these counter regulatory roles become perturbed. In obese individuals, ghrelin is not suppressed after eating, which results in continued hunger. In addition, leptin levels are elevated in obese individuals, but the body becomes resistant to its effects, and thus, leptin does not reduce satiety as it does in nonobese individuals.
True/False: Pharmacotherapy is recommended for all patients with obesity.
False. Drug treatment can be useful in combination with diet and exercise. It is recommended for people with BMI > 30 with no comorbidities or BMI > 27 with comorbidities.
Which neuropeptide plays a major role in the central control of appetite?
Neuropeptide Y—a potent-appetite stimulant.
True/False: Roux-en-Y gastric bypass is the most common surgical procedure recommended in the treatment of obesity.
True. Roux-en-Y gastric bypass surgery and the adjustable gastric band have become the most common bariatric procedures used in severely obese patients.
True/False: Jejunoileal bypass for morbid obesity is rarely performed because of a high incidence of serious intestinal and liver complications.
True. In addition, a characteristic arthropathy may complicate the postoperative course.
True/False: Morbidly obese individuals are at lower risk of malnutrition than normal weight individuals.
False. Overweight individuals are at higher risk of malnutrition. Up to 30% of obese individuals will be vitamin D deficient. In addition, obese patients may be deficient in antioxidants, calcium, and other important nutrients.
List nutritional deficiencies in identified patients who have undergone Roux-en-Y gastric bypass.
The main nutritional deficiencies include:
• Vitamin D
• Vitamin B12
• Folic acid
True/False: Kidney stones are a long-term complication of gastric bypass surgery.
True. Patients who have undergone gastric bypass surgery commonly have problems with calcium and vitamin D absorption and develop secondary hyperparathyroidism, which may result in metabolic bone disease and kidney stones.
True/False: Weight loss after Roux-en-Y gastric bypass surgery generally continues for 2–3 years before the weight stabilizes.
False: Most patients’ weight stabilizes approximately 12–18 months after surgery. Continued weight loss may be a sign of a complication of the surgery.
What is the generally accepted short-term mortality of bariatric surgery?
The 30-day mortality from bariatric surgery appears to be less than or equal to 1%. One recent prospective cohort study from 10 centers in the United States captured 6118 patients who underwent primary bariatric surgery. Eighteen deaths (0.3%) occurred within 30 days of surgery.
According to the most recent Cochrane review, bariatric surgery appears beneficial, but long-term morbidity and mortality studies are ongoing and data are limited.
• • • SUGGESTED READINGS • • •
Treasure J, Claudino AM, Zucker N. Eating disorders. Lancet. 2010 Feb 13;375(9714):583-593.
Flegal KM, Carroll MD, Ogden CL, Curtin LR. Prevalence and trends in obesity among US adults, 1999–2008. JAMA. 2010;303(3): 235-241.
NIH conference. Gastrointestinal surgery for severe obesity. Consensus Development Conference Panel. Ann Intern Med. 1991;115(12): 956-961.
American Gastroenterological Association medical position statement on obesity. Gastroenterology. 2002;123(3):879-881.
Bal B, Koch TR, Finelli FC, Sarr MG. Managing medical and surgical disorders after divided Roux-en-Y gastric bypass surgery. Nat Rev Gastroenterol Hepatol. 2010;7(6):320-334.