Diane is a 35-year-old woman who has struggled with obesity for most of her life. Her current body mass index (BMI) is 36. She has tried "every kind of diet you can imagine" but has always gotten stuck after losing the first 10 pounds and gets discouraged. She is not currently exercising regularly. She is concerned about all the skin tags on her neck and wants them removed if possible. She and her husband are talking about having another baby and she would like to be in better shape before she attempts pregnancy. She wants to discuss risks of pregnancy considering her weight and asks for any advice that you can give her on how to successfully lose weight. You obtain a random blood sugar because of her acanthosis and obesity (Figure 233-1). The result is 150 mg/dL and you order a fasting blood sugar (FBS) before her next visit, at which time you will remove her skin tags. After discussing diet and exercise, you encourage her to pursue Weight Watchers or a similar program.
Neck circumference enlargement with acanthosis nigricans and many skin tags in a woman with obesity and impaired glucose tolerance. (Reproduced with permission from Richard P. Usatine, MD.)
Obesity is defined as a BMI greater than or equal to 30. BMI is calculated as weight in kilograms divided by height in meters squared, rounded to 1 decimal place.1 Obesity in children is defined as a BMI greater than or equal to the age- and sex-specific 95th percentiles of the 2000 Centers for Disease Control and Prevention (CDC) growth charts. Adults with a BMI greater than 40 have substantially more serious health consequences, including heart disease and diabetes, and a reduced life expectancy.
Based on the National Health and Nutrition Examination Surveys, more than one-third of U.S. adults (34.9%) and 16.9% of children and adolescents are obese (2012).1 Slightly more women than men are obese (36.1% vs. 33.5%), although more men than women are classified as overweight or obese (BMI ≥25) (71.3% vs. 65.8%). The prevalence of obesity appears stable since 2003–2004.
The medical care costs of obesity in the United States (2014 dollars) are approximately $149.4 billion, with medical spending attributable to an obese individual of $1901 annually ($1239–$2582).2
ETIOLOGY AND PATHOPHYSIOLOGY
Obesity is a complex problem involving genetics, health behaviors, environment, and sometimes medical diseases (see "Differential Diagnosis" below) or drugs (e.g., steroids, antidepressants). The simplest explanation of obesity is an imbalance between intake (calories eaten) and output (physical activity).
The genetic contribution to interindividual variation in common obesity has been estimated at 40% to 70%....