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- Obesity refers to excess adipose tissue. Weight status is characterized by calculating the body mass index [BMI = body weight (kg)/(body height (m))2] and classified as underweight, normal weight, overweight, or obese:
- For adults, a BMI ≥30 kg/m2 is consistent with obesity.
- Obesity is associated with negative health outcomes:
- The increased risk of morbidity and mortality is most closely related to abdominal obesity.
- System(s) affected: Endocrine/Metabolic; Cardiac; Respiratory; Gastrointestinal; Musculoskeletal; Dermatologic; Mental Health
- Synonym(s): Overweight; Adiposity
BMI associated with the lowest risk of mortality increases as age increases.
- Predominant age: Incidence rises in the early 20s
- Predominant sex: Female > Male
- Mean prevalence of obesity among adults is 32.2% in the US.
- Overweight: 40% of men and 25% of women
- Obese: 20% of men and 25% of women
- Pediatric obesity is categorized as ≥95th percentile, as established by CDC growth curves, by age and sex.
- The incidence of obesity among the pediatric population has risen.
- Obesity during adolescence and young adulthood is strongly associated with obesity in adulthood.
- Risk factors include insufficient physical activity, consumption of sweetened beverages, and excess television viewing.
Etiology and Pathophysiology
- Obesity is caused by an imbalance among food intake, absorption, and energy expenditure.
- Underlying organic causes may be psychiatric disturbances, hypothyroidism, hypothalamic disorders, insulinoma, and Cushing syndrome.
- Medications: Corticosteroids, neuroleptics (particularly the “atypical” antipsychotics), and antidepressants
- Genetic syndromes such as Prader-Willi and Bardet-Biedl are responsible for a minor percentage of people with obesity.
- Studies are insufficiently powered to isolate genes as predictors of obesity.
- Parental obesity
- Sedentary lifestyle
- Calorie dense food
- Low socioeconomic status
- >2 hours/d of television viewing
- Encourage 1 hour of daily exercise, limited television viewing, and moderation in portion size.
- Avoid calorie-dense and nutrient-poor foods such as sweetened beverages and processed foods.
- Most patients underestimate daily calorie consumption.