Ep 148: A 55-Year-Old Man with Obesity
09:04 Share

This is Katarina Heidhausen, Executive Editor of Harrison's Principles of Internal Medicine. Harrison's Pod Class is brought to you by McGraw-Hills Access Medicine, the online medical resource that delivers the latest content from the best minds in medicine. And now, on to the episode. Hi, everyone. Welcome back to Harrison's Pod Class. We're your co-hosts. I'm Dr. Kathy Handy. And I'm Dr. Charlie Wiener, and we're joining you from the Johns Hopkins School of Medicine. Today's episode is about a 55-year-old with obesity.

Kathy, today's topic is very dynamic, and I think today's discussion is going to have to be followed up with a future episode. All right, sign me up. Okay, so today your patient is a 55-year-old man who comes asking to start pharmacotherapy for obesity. He's seen a lot of commercials on television, and he thinks he'd be a candidate. Okay, there definitely are a lot of commercials, but I'm going to need to know lots more about the history and physical exam. Okay, so he has a 10-year history of hypercholesterolemia and hypertension that's been treated with amylodipine and atorvastatin.

He's never had a myocardial infarction, and he has no evidence of sleep disordered breathing. Despite his best efforts to control his diet and increase exercise over the last five years, he's gained about 25 pounds. On physical examination, his blood pressure is 125 over 75. His BMI is 32 kilograms per meter squared, and his waist circumference is 40 inches. The rest of his vital signs are normal, and his only abnormality on the rest of your exam is an S4 when you listen to his heart.

His labs are notable for normal electrolytes and creatinine. His hemoglobin A1c is 6%, and last year it was 5.6%. All right, let's take a step back for a second and just remind folks why obesity is such an important topic.

More than 70% of U.S. adults are considered to be overweight or have obesity, and the prevalence of obesity is increasing rapidly in most of the industrialized world. Children and adolescents are also becoming more obese, indicating that the current trends will accelerate over time.

Obesity is associated with an increased risk of multiple health problems, including hypertension, type 2 diabetes, dyslipidemia, obstructive sleep apnea, non-alcoholic fatty liver disease, degenerative joint disease, and even some cancers. And it appears that reducing weight in obese individuals can mitigate many of those risks. Okay, but what about our patients?

So our patient qualifies as having class one obesity by his BMI being over 30, but less than 35. I'm glad you mentioned his waist circumference. BMI can be high without obesity in muscular people, but waist circumference is an indicator of excess abdominal fat and it's independently associated with a higher risk of metabolic syndrome, diabetes, and cardiovascular disease.

Measurement of the weight circumference is a surrogate for visceral adipose tissue, and it should be performed in the horizontal plane right above the iliac crest. The cutoffs are ethnicity-based because some populations from the Asia-Pacific region appear to be at risk for glucose and lipid abnormalities at lower body weights. Our patient with a 40-inch waist is over the threshold for any ethnicity.

Okay, so let's get to the question, which is asking, which of the following statements regarding a therapeutic approach to reducing obesity is true? Option A, a low-carbohydrate diet leads to greater weight loss than a low-fat diet. B, glucagon-like peptide analogs have demonstrated greater than 5% sustained weight loss in randomized trials. C, glucagon-like peptide 1 analogs inhibit insulin release and augment glucagon release from the pancreas.

Option D is lifestyle activities are less effective than a structured exercise program for weight loss. And option E is the efficacy of oralistat is limited by its systemic side effects. Well, the primary goals of treatment are to improve obesity-related comorbid conditions, quality of life, and reduce the risk of developing future obesity-related complications.

Therapy for obesity always begins with lifestyle management, and that includes attention to dietary habits, physical activity, and then behavior modification. Yeah. So two of the options I mentioned relate to lifestyle. Are either of those true?

So neither is true. Remember, the primary focus of diet therapy is to reduce overall calorie consumption. Numerous randomized trials comparing diets of different macronutrient compositions, such as low-carb diets, low-fat diets, Mediterranean diets, they've shown that weight loss depends primarily on reduction of total caloric intake and adherence to the prescribed diet and not the specific proportions of carbohydrate, fat, and protein in the diet.

I would also add that some recent studies have not demonstrated a profound effect on some other recent dieting trends such as time-limited eating or periodic fasting. Okay, well I know activity is important. What about lifestyle activities versus structured workouts?

Although exercise alone is only moderately effective for weight loss, the combination of dietary modification and exercise is the most effective behavioral approach for the treatment of obesity. The most important role of exercise appears to be in the maintenance of the weight loss. Studies have demonstrated that lifestyle activities are as effective as structured exercise programs for improving cardiorespiratory fitness and weight loss. What do you mean by lifestyle activities?

Things like simple ways to add physical activity into the normal daily routine, such as brisk walking, using the stairs, household work, yard work, engaging in sports, asking the patient to wear a pedometer or accelerometer to monitor total accumulation of steps or energy expenditure as part of the activities of daily living can be a useful strategy.

Step counts are highly correlated with activity level. And it's important to reduce sedentary behavior, which is associated with all-cause mortality and cardiovascular disease mortality in adults. Okay, so in order to find the right answer, we're down to the medications. We've mentioned Orlistat and the glucagon-like peptide 1 analogs.

The GLP-1 analogs certainly have hit the scene with a flourish recently. I'm sure those are the television commercials that our patient saw and simulated his visit. Which of those options is true?

Yeah, so these are game changers and lots of work is ongoing. We'll definitely have to revisit this topic in the future. But GLP-1 analogs acts as an incretin hormone to augment glucose-induced insulin secretion, inhibit glucose-induced glucagon secretion, inhibit both gastric emptying and stimulate receptors in the hypothalamus to reduce feeding.

These agents have demonstrated over 5% sustained weight loss in randomized trials. There is still a lot of work ongoing regarding the duration of the response and whether they can be discontinued at some point, plus new agents active in this pathway are coming out. So stay tuned and definitely more to talk about. Okay, so the option B, the 5% weight loss, sustained weight loss, that's the true option. Let's finish with Orlistat. We don't talk about that very often.

Orlistat is an inhibitor of pancreatic and gastric lipases, which are required for the hydrolysis of dietary fat into fatty acids and monoacylglycerols. It acts in the lumen of the stomach and small intestine and blocks the digestion and absorption of about 30% of dietary fat. But does it cause weight loss?

Yes. Multiple randomized double-blind placebo-controlled studies have shown that after one year, Orlistat produces about a 10% weight loss. Because Orlistat is essentially not absorbed from the gastrointestinal tract, it has only local and not systemic side effects related to the malabsorption of dietary fat. Over 10% of patients report side effects such as flatus with discharge, fecal urgency, fatty or oily stool, and increased defecation.

Those don't sound nice. I can see why people prefer the GLP-1 analogs. Okay, so the teaching points today are that obesity is a growing public health problem, not only in the U.S., but worldwide, and it has substantial effects on health. Patients with an elevated BMI or an elevated waist circumference should be advised on lifestyle modifications and considered for medical therapy. The GLP-1 analogs are the newest form of effective medical therapy.

You can find this question and other questions like it in the Harrison Self-Review Book and online. And you can read more about this topic in the Harrison's chapters on the pathobiology of obesity and evaluation and management of obesity. Visit the show notes for links to helpful resources, including related chapters and review questions from Harrison's, available exclusively on Access Medicine. If you enjoyed this episode, please leave us a review so we can reach more listeners just like you. Thanks so much for listening.