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Source: Chen JT, Sheehan AH, Yanovski JA, and Calis KA. Obesity. In: DiPiro, JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. http://accesspharmacy.com/content.aspx?aid=8013538. Accessed July 29, 2012.

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  • State of excess body fat as determined by measures of adiposity
    • Imbalance between energy intake and energy expenditure over time, resulting in increased energy storage
  • Overweight: body mass index (BMI) 25–29.9
  • Obese: BMI 30–39.9
  • Severely obese: BMI 40 and over

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  • Specific etiology of obesity unknown, but multifactorial and related to varying contributions from genetic, environmental, and physiologic factors.

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  • Many neurotransmitters and neuropeptides stimulate or depress brain’s appetite network, impacting total calorie intake.
  • Net balance of energy ingested relative to energy expended over time determines degree of obesity.
    • Metabolic rate largest determinant of energy expenditure.
    • Amount of physical activity contributing factor.
  • Adrenergic stimulation activates lipolysis in fat cells and increases energy expenditure in adipose tissue and skeletal muscle.
    • Major types of adipose tissue
      • White, which manufactures, stores, and releases lipid
      • Brown, which dissipates energy via uncoupled mitochondrial respiration

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  • Prevalence
    • Varies by sex among racial and ethnic minorities in United States.
    • Increases with age until eighth decade
    • Increased with lower socioeconomic class and educational achievement

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  • Increased level of physical activity
  • Decreased caloric intake relative to physical activity

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  • Sedentary lifestyle
  • Association with other obese individuals
  • Lower socioeconomic status
  • Lower educational achievement

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  • Amount of excess fat and its distribution regionally in body important clinically.
    • Central obesity reflects high levels of intra-abdominal or visceral fat associated with development of hypertension, dyslipidemia, type 2 diabetes, and cardiovascular disease.

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Signs and Symptoms

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  • BMI >25, calculated as weight (kg) divided by square of height (m2).
  • Waist circumference (WC) >40 inches (102 cm) for men and >35 inches (89 cm) for women (narrowest circumference between the last rib and top of iliac crest)
  • Both of above are independent predictors of disease risk (Table 1).

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Table Graphic Jump Location
Table 1. Classification of Overweight and Obesity by Body Mass Index (BMI), Waist Circumference, and Associated Disease Risk
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Means ...

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