Obesity Case File

Obesity Case File

Eugene C. Toy MD, Donald Briscoe, MD, FA  AFP, Bruce Britton, MD, Joel J. Heidelbaugh, MD, FA  AFP, FACG

Case 33

A 20-year-old woman comes to clinic for an annual physical examination. She has no complaints. She has no significant medical or surgical history. She is currently taking oral contraceptive pills because of her irregular menstrual cycles. She attained menarche at age 13 and has had irregular cycles since. She has never been sexually active. Her family history is positive for hypertension and obesity in both her parents. On examination, her blood pressure (BP) is 120/85 mm Hg, her pulse is 78 beats/min, and her respiratory rate is 14 breaths/min. Her weight is 188 lb, and she is 63-in tall. Her physical examination is unremarkable except for a brownish/black, velvety thickening of the skin on the back of her neck, hirsutism, and abdominal obesity.

⯈ What are the clinical issues that need to be addressed during this preventive visit?

⯈ What is your next step in the evaluation of this patient?

⯈ What are the therapeutic options available for this patient?

ANSWER TO CASE 33:

Obesity

Summary: A 20-year-old obese woman presents for a routine examination. Along with her abdominal obesity, she has irregular menstrual cycles, acanthosis nigricans, and hirsutism.

• Clinical issues to address: Obesity and possible polycystic ovarian disease.
• Next steps in evaluation: Calculate a body mass index (BMI), measure waist circumference, repeat blood pressure. Order laboratory tests to measure fasting glucose, lipids, thyroid-stimulating hormone (TSH), and liver enzymes.
• Therapeutic options: Assess her interest in losing weight. If she is interested, collaborate with the patient to devise weight-loss goals and advise on diet and physical activity to achieve these goals. If she is not interested, advise on the health benefits of weight loss and address other risk factors. In either case, arrange follow-up. At subsequent visits, you can consider adding pharmacotherapy as an adjunct to diet and exercise.

ANALYSIS

Objectives

1. Understand the etiology and pathogenesis of obesity.
2. Know other comorbid conditions associated with obesity.
3. Learn the diagnostic criteria for obesity and the metabolic syndrome.
4. Understand the therapeutic options available for the management of obesity.

Considerations

Obesity is a chronic and stigmatizing disease that begins early in life. Increased caloric intake, decreased physical exertion, and genetic predisposition are common causes of obesity. Routine physical examination visits serve as a good platform to address issues related to obesity and its associated comorbid conditions. This visit should be taken as an opportunity to address obesity, metabolic risk, and its management.

In this case, this patient's weight is 188 lb, and she is 63-in tall; thus, her BMI is 33.5 kg/m3.Further measurements included a waist circumference of 36 in and a repeat blood pressure of 125/85 mm Hg. Her laboratory test results included total cholesterol of 202 mg/ dL, high-density lipoprotein (HDL) cholesterol of 35 mg/ dL, low-density lipoprotein (LDL) cholesterol of 120 mg/ dL, and triglycerides of 172 mg/ dL. Her fasting glucose was 104 mg/ dL, and she had normal renal and liver function tests.

Increased body weight is a major risk factor for the development of disease and for premature death. The metabolic syndrome is an important risk factor for subsequent development of type 2 diabetes and cardiovascular disease (CVD). The metabolic syndrome presents in 5% of the population at normal weight, 22% of those who were overweight, and 60% of those who were obese. She has metabolic syndrome based on her abdominal circumference, increased triglycerides, low HDL, and mildly elevated LDL cholesterol levels. She may also need further investigation for the presence of polycystic ovarian syndrome (PCOS) because of her obesity, hirsutism, and history of irregular cycles. PCOS should be a consideration in patients with chronic anovulation, ovarian cysts, and evidence of hyperandrogenism. Both the metabolic syndrome and PCOS are very closely associated with obesity and insulin resistance.

Based on the provided information, in this situation, the key clinical implication of these diagnoses is identification of a patient needing aggressive lifestyle modification focused on weight reduction and increased physical activity.

Approach To:

Obesity

DEFINITIONS

BODY MASS INDEX: A measurement of the relative composition of lean body mass and body fat, calculated as (weight in kilograms)/(height in meters)2.

METABOLIC SYNDROME (syndrome X, insulin resistance syndrome): A constellation of metabolic abnormalities that confer increased risk of cardiovascular disease and diabetes mellitus. Major features include central obesity, hypertriglyceridemia, low HDL cholesterol, hyperglycemia, and hypertension.

OVERWEIGHT: Defined as BMI greater than or equal to 25 kg/m2, the point at which all-cause, metabolic, cancer, and cardiovascular morbidity begins to rise.

OBESITY: A state of excess adipose tissue mass. Defined by most authorities as BMI greater than or equal to 30 kg/m2. Morbid obesity is defined as a BMI greater than or equal to 40 kg/m2. Super obesity is defined as a BMI greater than or equal to 50 kg/m2.

SATIATION: Level of fullness during a meal.

SATIETY: Level of hunger after a meal.

CLINICAL APPROACH

Obesity is a chronic and easily diagnosed disease that is associated with life threatening morbidity and mortality. Data from the National Health and Nutrition Examination Surveys (NHANES) show that in 2011 to 2012, 16.9% of 2- to 19-year-olds and 35.1 % of adults aged 20 or older were obese. Overall, there was no significant change from 2003 to 2004 through 2011 to 2012 in obesity in 2- to 19-year-olds, or obesity in adults.

Metabolic Syndrome

Current minimum estimates are that the prevalence of metabolic syndrome in the United States is at least 34.5% using the Adult Treatment Panel (ATP) III criteria (Table 33-1). The metabolic syndrome is an important risk factor for subsequent development of type 2 diabetes and cardiovascular disease. Thus, the key clinical implication of a diagnosis of metabolic syndrome is identification of a patient needing aggressive lifestyle modification focused on weight reduction and increased physical activity.

Diagnostic Tools

BMI is used as a measure of weight status and aid to predict risk of disease as it generally correlates well as an estimate of total body fat. However, BMI is not as accurate a measure of overweight/obesity in patients with heart failure, pregnant women, body builders, professional athletes, elderly patients, and certain ethnic groups. Moreover, abdominal obesity is associated with increased risk for hypertension, heart disease, dyslipidemia, and diabetes. Additional measurements, like waist circumference, and waist-to-hip ratio, need to be used to accurately identify the population at risk. Direct measurement of percentage of body fat may also provide additional information. Table 33-2 lists the classification of overweight/ obesity based on BMI.

Along with the measurements mentioned earlier, a health history, physical examination, and focused laboratory workup should be performed to look for complications and comorbid conditions. Any previous weight-loss efforts, recent smoking cessation, daily physical activity levels, and eating habits should be assessed to identify factors that might be contributing to weight gain and obesity. A fasting glucose and glycosylated hemoglobin level should be measured to evaluate for diabetes mellitus and impaired glucose tolerance. The presence of acanthosis nigricans-a velvety, hyperpigmented thickening of the skin commonly found on the neck and axillary regions-may also be a sign of insulin resistance. Fasting lipids should also be measured, both to evaluate for the presence of metabolic syndrome and for the assessment of the patient's risk for cardiovascular disease. TSH should be measured to screen for hypothyroidism. Liver enzymes should be requested, as abnormal results may indicate the development of a fatty liver.

Pathogenesis

Energy balance is the relationship of energy intake to energy expenditure. When more energy is expended than taken in, weight loss ensues. When the intake of energy exceeds the amount expended, weight gain occurs. In all persons, obesity is caused by ingesting more energy relative to the amount of energy expended. Energy balance is affected by genetic, physiologic, and environmental factors.

It has been estimated that genetic background can explain 40% or more of the variance in body mass in humans. The genetic component is complex and involves the interaction of multiple genes. However, the marked increase in obesity cannot be completely attributed to genetics. Social factors such as lower education level, lower socioeconomic class, and diet composition are all associated with high risk of obesity. Likewise, physiologic factors such as various gut hormones, level of spontaneous physical activity (fidgeting), and age-related decline in energy expenditure are key determinants in regulation of food intake and energy expenditure. An increase in energy consumption with a decrease in physical activity is thought to be the main contributor to the current obesity epidemic. Among numerous issues, the availability of convenience foods and the increase in palatability and serving size, compounded with industrialization leading to a sedentary lifestyle, has led to an altered energy balance.

Health Hazards Associated With Obesity

Obesity is a risk factor for the development of diabetes and cardiovascular disease. It is a risk factor for numerous other medical conditions (Table 33-3). In general, greater BMI is associated with more health complications and grade II or higher obesity is associated with greater risk of mortality. Also, the more complications that develop, the more difficult it becomes to manage the underlying obesity. For example, a person with degenerative arthritis and heart disease may have significant symptoms during exercise, impairing his or her ability to expend more energy in an effort to lose weight.

Treatment

Treatment of obesity should begin in patients with a BMI greater than 25 or who have visceral obesity, documented by increased waist circumference greater

than 40 in men and greater than 35 in women or a waist-to-hip ratio greater than 0.9 in men and greater than 0.85 in women. Weight loss of as little as 5 lb reduces the risk of developing comorbid conditions. Developing a treatment plan for obesity is complex and should use a combination of dietary restrictions, increased physical activity, and behavior therapy as a gold standard.

Dietary intervention is the cornerstone of weight-loss therapy. Most diets work in two principal dimensions: energy content and nutrient composition. The National Heart, Lung, and Blood Institute (NHLBI) recommend initiating treatment with a calorie deficit of 500 to 1000 kcal/ d compared with the patient's habitual diet. This reduction produces a weight loss of 1 to 2 lb/wk (0.45 to 0.91 kg/wk). Loss of more than 5% of initial body weight can improve CVD risk. There are different kinds of specific dietary modifications recommended, but they all work based on calorie restriction. The selection of a diet should be based on patient preferences to promote optimal dietary adherence, a key determinant of weight loss irrespective of the type and nutrient composition of the diet. In addition, calorie restriction should not compromise the nutrient content of the diet; patients should still aim for a balanced meal.

The addition of exercise training to a diet program can add to the weight loss. However, physical activity alone is not an effective method for achieving weight loss. Although increasing physical activity is not effective for weight loss when used alone, physical activity is very important for long-term weight management and cardiovascular health benefits. Physical activity can improve insulin sensitivity and glycemic control, decrease abdominal fat, and reduce cardiovascular risk. Patients should engage in moderate to vigorous physical activity for at least 30 min/ d, 5 to 7 d/wk, both to maintain weight loss and for the independent health benefits of exercising.

The purpose of behavior modification therapy is to help patients identify and make long-term changes in their eating and physical activity habits that contribute to obesity. T he targets of behavior modification are avoiding triggers, maintaining dietary diaries, using portion-controlled plates, slowing rate of eating to enhance satiation, avoidance of high-risk situations, increasing phy sical activity, and breaking repetitive behaviors, such as watching TV while eating.

Pharmacotherapy

Table 33-4 lists the medications commonly used in the treatment of obesity. Pharmacologic therapy may be offered to those with a BMI greater than 30, or

BMI of 27 to 30 with comorbid conditions. Orlistat, lorcaserin, and phentermine/topiramate are US Food and Drug Administration (FDA) approved for long-term weight-loss management. All of these approved medications have generally been found to have modest weight loss over placebo and often are limited in efficacy due to side effects and/ or cost.

With the exception of orlistat, which inhibits the absorption of dietary fat, all medications approved for obesity act as anorexiants. Anorexiant medications increase satiation, satiety, or both, by affecting the monoamine system in the hypothalamus. Increasing satiation results in a reduction in the amount of food eaten, whereas increasing satiety reduces the frequency of eating. The FDA-approved medications, which should be used as adjuncts to diet, exercise, and behavioral treatments, are generally recommended to be used short term. Their use should be tapered off after prolonged use or if there is lack of efficacy. Metformin and exenatide, medications approved for treatment of type 2 diabetes mellitus, may be a useful adjunct for weight loss in patients with comorbid obesity. Metformin can also help with weight loss in patients with polycystic ovary syndrome.

Many previously approved medications for weight loss have been removed from the market due to significant risks greater than benefits. Over-the-counter weightloss medications and supplements have similar risk-benefit profiles or have limited research for safety and efficacy.

Bariatric Surgery

Patients with a BMI greater than 40 who have failed diet and exercise (with or without drug therapy), or greater than 35 with serious comorbid conditions, are potential candidates for surgical treatment of obesity. Weight-loss surgeries fall into one of two categories: restrictive and restrictive-malabsorptive. Restrictive surgeries, such as laparoscopic adjustable gastric banding, limit the amount of food the stomach can hold and slow the rate of gastric emptying. Restrictive-malabsorptive bypass procedures, such as the Roux-en-Y gastric bypass, combine the elements of gastric restriction and selective malabsorption.

The two most common surgeries done are Roux-en-Y gastric bypass and laparoscopic adjustable gastric banding, or "lap banding:' The Rouex-en-Y procedure involves the construction of a small (10-30 mL) gastric pouch that empties into a segment of jejunum. With the small pouch and the small outlet to limit caloric intake, the Rouex-en-Y is mostly a restrictive procedure with some degree of associated malabsorption. Surgical mortality rate from bariatric surgery is generally less than 1 % but varies with the procedure, patient's age and comorbid conditions, and experience of the surgical team. The most common surgical complications include stomal stenosis or marginal ulcers (occurring in 5%-15% of patients) that present as prolonged nausea and vomiting after eating or inability to advance the diet to solid foods.

In lap banding, an adjustable silicone gastric band is laparoscopically placed around the upper stomach just distal to the gastroesophageal junction. The band has a balloon connected to a subcutaneously implanted port, which can be inflated or deflated to reduce the circumference of the band. Complications of the banding procedure are less common and less severe than in gastric bypass, but the long-term weight loss may also be less. The adjustable band allows for the flexibility of addressing various nutritional demands after the surgery. For example, the band can be adjusted to have the stoma widened to accommodate a greater demand for caloric and fluid intake when a patient becomes pregnant.

COMPREHENSION QUESTIONS

33.1 A 15-year-old adolescent boy is brought into the clinic by his mother. He has been experiencing chest pain, shortness of breath, and is having increased episodes of asthma exacerbation. He is 5 ft 10 in in height and weighs 399 lb. An ECG in the office shows a normal sinus rhythm. He is unable to participate in school athletics due to his weight and has little physical activity after school. He has friends, but has some esteem issues because of being so large. He often finds it hard to find current trendy clothes in his size, but says it's ok because he is not the largest person at his school. His mother, who is also morbidly obese, is worried that he will have a heart attack and wants him to lose weight. Which of the following patients has the best evidence to be a candidate for bariatric surgery as initial treatment for obesity?

A. A man with a BMI of 32 and arthritis of the knees.

B. A woman with a BMI of 33 and type 2 diabetes.

C. A woman with a BMI of 42 but no identifiable complications.

D. Any obese patient who desires bariatric surgery should have it offered.

33.2 A patient you have been seeing for 10 years recently lost his health insurance because his BMI is too high. He was born with achondroplasia and is 4 ft 8 in in height and weighs 192 lb. He has been in good health and takes no medications. On examination, his BP is 122/76 mm Hg, pulse 56 beats/min, and respiratory rate 16 breaths/min. For which of the following patients is a BMI measurement most likely to be an accurate assessment of obesity?

A. A bodybuilder with a BMI of 38

B. A pregnant woman with a BMI of 31 in her 37th week of gestation

C. A man with congestive heart failure, pitting edema, and a BMI of 30

D. A hypertensive woman with a BMI of 32

33.3 A 34-year-old Hispanic woman comes to clinic to discuss weight management. She is currently 5-ft 2-in tall and weighs 265 lb. She says she always had a hard time managing her weight as a child, but let things get out of control when she was living on her own in college. She has had two children in the past 5 years. She gained 50 lb with the first child and lost 30 lb. With the second child she gained 35 lb and lost 10 lb. She has tried many fad diets where she initially loses weight but eventually gains it back. She exercises some but is limited by osteoarthritis of the knees. She has thought about gastric bypass but is fearful of undergoing a surgical procedure. Which of the following medications may be used for the long-term management of obesity?

A. Orlistat

B. Phendimetrazine

C. Dextroamphetamine

D. Phentermine

ANSWERS

33.1 C. Bariatric surgery can be effective but carries significant risks. The best evidence is for people with a BMI of greater than 40 who have failed diet and exercise (with or without drug therapy) or with a BMI of greater than 35 and obesity-related complications. Grade 1 obesity with diabetes mellitus or significant medical conditions related can be considered for bariatric surgery, but the evidence of benefit over risk is less robust.

33.2 D. A BMI reading will not accurately assess the ratio of lean body mass to body fat in highly muscled persons (weightlifters, athletes), persons with decreased muscle mass (elderly), in pregnant women, and in symptomatic congestive heart failure.

33.3 A. Orlistat is indicated for the long-term treatment of obesity. All of the pure stimulant medications should be for short-term use only.

CLINICAL PEARLS

⯈ Obesity is a chronic disease that is reaching epidemic status in the United States and worldwide.

⯈ BMI is a common tool used to grade obesity, but in certain cases it may be inadequate.

⯈ Obesity treatment should always include dietary restriction, increased activity, and behavioral modifications.

⯈ Even 5% to 15% weight loss can significantly reduce the complications associated with obesity.

REFERENCES

Bray GA. Contemporary Diagnosis and Management of Obesity and the Metabolic Syndrome. 4th ed. Newton, PA: Handbooks in Healthcare; 2011. 

Centers for Disease Control and Prevention (CDC). Available at: www.cdc.gov/obesity. Accessed November 7, 2015. 

Dyson PA. The therapeutics of lifestyle management on obesity. Diabetes Obes Metab. 2010;12(11): 941-946. 

Flier JS, Maratos-Flier E. Biology of obesity. In: Kasper D, Fauci A, Hauser S, et al., eds. Harrison's Principles of Internal Medicine. 19th ed. New York, NY : McGraw-Hill; 2015. Available at: http:// accessmedicine.mhmedical.com. Accessed May 25, 2015. 

Grundy SM, Smith SC, Jr. Metabolic syndrome, obesity, and diet. In: Fuster V, Walsh RA, Harrington RA, eds. Hurst's the Heart.13th ed. New York, NY: McGraw-Hill; 2011. 

Moyer VA. U.S. Preventive Services Task Force. Screening for and management of obesity in adults: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2012 Sep 4;157(5):373-378. 

Ogden CL, Carroll MD, Kit BK, Flegal KM. Prevalence of childhood and adult obesity in the United States, 2011-2012.JAMA. 2014;311(8):806-814.

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