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- Obesity is the state of excess adipose tissue. Weight status can be defined using 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 (1), and the highest risk for increased morbidity and mortality is found in the context of 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 35% in the United States (2).
- 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.
- 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 screen time.
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 can contribute to obesity, including corticosteroids, neuroleptics (particularly 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
- Consumption of calorie-dense food
- Low socioeconomic status
- >2 hours per day of television viewing
- Encourage at least 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.