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A 35-year-old woman presents to establish care with you. She has no specific concerns. On examination, you observe an obese body habitus and calculate her body mass index (BMI) at 36.5 kg/m2 based on a weight of 209.5 lb and a height of 63.5 inches. When you raise concern about obesity and potential comorbidities, she reveals that she is unhappy with her current weight and has recently embarked on a diet plan to lose weight. She believes she has been at or near her current weight for the past 4 years. She last felt comfortable with her weight when she was 145 lb.

  • What additional history would help distinguish whether she has primary versus secondary weight gain?
  • How do you use the history to screen for obesity-related comorbidities?

Weight gain is an absolute increase in body weight. Weight gain is usually a consequence of accumulation of excess body fat, although processes such as edema and ascites can cause substantial weight gain. Weight gain is common and a significant public health concern. Regardless of baseline weight, weight gain can lead to adverse health consequences and to the development of obesity, a major cause of morbidity and the second leading cause of preventable deaths in the United States. Over the last 2 decades, the prevalence of obesity has risen dramatically; currently, 64% of Americans are overweight, and 30% are obese.

Primary weight gain is the accumulation of adipose tissue that results from an imbalance between caloric intake and energy expenditure. Less commonly, weight gain is due to secondary causes such as endocrine disorders and medication side effects. The patient history serves 3 main goals: (1) to distinguish between weight gain caused by abnormal fluid retention and weight gain caused by body fat accumulation; (2) to identify the contributing factors or secondary causes of excess fat accumulation and; (3) to screen for serious medical complications caused by weight gain or obesity.

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Body mass index (BMI)BMI is a measure of relative weight for height. It is defined as weight in kilograms divided by the square of height in meters.1 It correlates with other measures of body fat and is used as an inexpensive measure of weight-related health risk.
ObesityA chronic disorder of excessive weight characterized by an excessive accumulation of body fat and a high health risk. It is defined as a BMI ≥ 30 kg/m2 and further subdivided into class I (BMI 30–34.9 kg/m2), class II (BMI 35–39.9 kg/m2), and class III obesity (BMI ≥ 40 kg/m2).1
OverweightWeight above the established normal range but below the criteria for obesity. It is defined as a BMI between 25 and 29.9 kg/m2.1

Most weight gain is primary weight gain, resulting from excess body fat accumulation due to physiologic or behavioral changes that result in ...

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